A massive intelligence investigation is under way after police confirmed the final death toll from the London bombings will be at least 50. Religious leaders of all faiths have come together to condemn the attacks. BBC News correspondents report on the latest developments.
Gavin Hewitt : King's Cross : 2200 BST
This has been something of an unreal day. The station here has been operating almost normally.
The roads here are busy, it looks like the London we know.
Yet right now, under the ground, there are search teams still trying to reach a carriage where they believe are many bodies.
Gareth Furby : Tavistock Square : 1858 BST
There are flowers now starting to be left in tribute to those that lost their lives here.
The investigations here are continuing, but the hunt for the bombers has only just begun.
Duncan Middleton : Euston Station : 1820 BST
There are lots of police here but that's not surprising: we're only a few hundred yards from the crime scene of Tavistock Square
But if you walk into Euston Station all the trains are running, and apart from being a little quiet for a Friday night, it could be any other day.
Philippa Thomas : King's Cross : 1717 BST
People are starting to lay flowers here.
One little note says "London we love you" and people have also written poems.
They are leaving their heartfelt words which is all they can muster after the atrocity which has taken at least 20 lives below the platforms where we stand.
Richard Lister : Royal London Hospital : 1710 BST
Those who heard the Queen's speech here said they were quite emotionally affected and that the Queen was too.
She met porters, nurses, doctors and heard a lot of stories from yesterday.
The staff here clearly feel it was important for them and that it gave the patients a lift too.
Philippa Thomas : King's Cross : 1630 BST
Today we've been finding out how London's transport system has been getting back to normal. We've talked to chaplains who were here yesterday and emergency services officers who were traumatised by what they saw.
You get a sense of a support network in place, an operation rolling along at the front line, and of many backing it up.
We've also seen members of the Royal Family out and about in hospitals, where we know there are 80 victims or so, and the Queen and Prince Philip at the Royal London Hospital in Whitechapel.
Prince Charles and the Duchess of Cornwall have been thanking staff, meeting some of the survivors and just hearing their stories. We've heard from a member of the Salvation Army how important it is for people to have someone to listen. It is important for those who have been through something like this.
Gordon Corera : Television Centre : 1620 BST
These attacks really did come out of the blue. The threat level was taken down a notch (there are seven notches on it) within the last month. The reason was that they didn't see any threats at an operational stage. What this means is that this group that carried out the attacks were under the radar.
These devices were not made with things you can buy in a gardening shop - they were high explosives. There is a debate about whether these were suicide bombers or whether they are still at large. Intelligence agencies in the UK are liaising with international agencies to see if there are any signs or clues which might help them in their manhunt.
Liam Allen : Liverpool Street : 1610 BST
In the City of London, Dutch trader Pieter Maat, 29, said he has been "very impressed" by British stoicism in the face of adversity and although he has only lived in the UK for a year and a half, he said he was proud to be a part of that tradition.
He stressed the importance of continuing as normal and said he reflected the thoughts of all his colleagues in saying that to have stayed at home today would be to have given the bombers the impression that what they did on Thursday had worked.
Jon Brain : Royal London Hospital : 1545 BST
The Queen arrived here just after 3pm by helicopter on top of the hospital which is the same helipad which took doctors out to incidents yesterday. She went to the cafeteria to thank the team for their efforts yesterday and talked to two patients.
There are nineteen casualties being treated here. There were initially 200, some brought by double-decker bus but most have been discharged. Of the remaining nineteen, seven are in a critical condition and staff are particularly concerned about two of those.
The hospital believe the emergency plan went better than expected; partly because fortuitously there was a meeting of London Air Ambulance, paramedics and doctors. They were immediately taken out to deal with casualties in various locations.
I've seen lots of relatives of patients go in. And I saw one man who is looking for his niece who he hasn't been able to trace and there are people like that here. Two of the patients in this hospital haven't been identified yet so that also happens here.
Dominic Casciani : Aldgate security cordon : 1520 BST
Religious leaders from across the East End have come together in a remarkable demonstration of unity by holding a silent vigil outside Aldgate Station.
Jew, Muslim, Christian, Sikh and Buddhist stood together and remembered in silence those who had died and prayed for those still suffering.
As they stood silently on the edge of the forensic cordon, in the distance we could see specialist police officers continuing their mission to work out what happened beneath our feet.
If the bombers had hoped to sow fear and breed division in this most multicultural of cities, then the East End's religious communities have delivered them a message: This city will not be divided.
Rahul Tandon : East London Mosque : 1500 BST
There was a Friday sermon given by the imam of the mosque. In it he talked about Islam being there to save life. He also talked about the people responsible for yesterday's attack describing them as criminals.
He tried to reassure the muslims who are fearful at the moment. Some of the people I have talked to at the mosque today feel they are being viewed differently when they travel on the tube. They say people stare at them and that leads them to feel slightly scared at the moment.
Liam Allen : Shepherds Bush, West London : 1450 BST
The police cannot afford to take any chance after yesterday's atrocities. An old hi-fi system, dumped by the side of a post box, proves to be cause for concern.
Three squad cars race to the scene and people are cleared from the surrounding area and kept back by officers. After a short while it is deemed safe and officers leave the areas, presumably to return to the job of maintaining the high visibility police presence seen across the capital on Friday.
On a normal day a dumped old hi-fi may not have attracted so much attention. The officers expressed their dismay that someone could have been so irresponsible as to dump such an item.
Dominic Casciani : East London Mosque : 1435 BST
Faith leaders from across the East End of London are holding a major event to show that their communities are united in opposing terror. One of those who has spoken most passionately about the need for communities of all backgrounds to rally in support of their Muslim neighbours has been Monsignor John Armitage of the Catholic Church.
"For many years, the IRA had a campaign of bombing, and when they bombed Birmingham I was a student in the city.
"Let me tell you that anybody with the briefest understanding of religion should understand that religion has nothing to do with terrorism.
"When people talked of the IRA being Catholic terrorists, they were no such thing.
"This is why I stand today in solidarity with people of faith, and people of no faith here in the East End."
Luisa Baldini : Kings Cross : 1410 BST
The hustle and bustle has returned - many regular train services are running from Kings Cross and the station concourse is absolutely packed.
The entrance to the tube is baricaded so that the investigation can begin. Just how that is progressing is unclear because the Metropolitan Police have told that its extremely difficult to try to even reach the train and they're worried the tunnel may even collapse. The British Transport Police however are telling us that a fingertip search has begun in three of the carriages.
What has been confirmed is that the device was in the first carriage - on the floor in the standing area near the first set of doors. However more bodies have yet to be recovered.
Frank Gardner : Television Centre : 1405 BST
We have been attacked but we have been a target for a very long time. Britain has been targeted by groups sympathetic to Al Qaeda for some years now ever since British troops went into Afghanistan and made an enemy of them then. The threat has been real for some years. We might have these attacks as long as the Iraq conflict lasts and as long as western forces remain in that country.
It's not absolutely proven that Al Qaeda-linked groups are behind these attacks in London but that's where the finger of suspicion is pointing. But yesterday's attacks bore many of their hallmarks.
Daniel Boettcher : In helicopter near London : 1338 BST
The overwhelming impressing from here is that things are getting back to as near normal as possible. There's an air exclusion zone over the city but looking towards Liverpool Street and Aldgate, the main road bridges look pretty much empty and traffic is moving freely.
In the financial centre and looking at one of the squares you'd expect it to be pretty busy with business people but there's hardly anybody there. Whether this is because people have been heeding the advice to stay away we don't know at the moment. We'll have to wait until Monday's rush hour to see just how confident people are about coming back to work.
Philippa Thomas : Kings Cross : 1335 BST
It's still really tense here.
We've just had an evacuation, with everyone forced out onto the pavement. It turned out to be a false alarm though.
Everyone is taking security alerts really seriously
Claire Heald : Kings Cross : 1325 BST
Rev Liam Johnston, is co-ordinating the chaplains offering support for police officers at King's Cross. "It's something that they have trained for but the training never really prepares you for the real thing," he said.
"From what they have said it is a scene down there of total carnage but they have to block that out and just treat it as a job until they come above ground - it's at that point that they begin to assess what they have been doing.
"We talk to them to try and share a little of the love of God and some compassion. It might sound trite but until you have been through something like that you don't really understand how much people cling onto the spiritual side of life."
Gill Higgins : Royal London Hospital : 1320BST
Due to the incredible efforts of staff the
vast majority of people who came in yesterday have been treated and have been able to go home.
It's been a very different picture from yesterday when over 200 people needed emergency treatment, but 19 patients do still remain here.
Dr Alistair Wilson, clinical director of Accident and Emergency, said there was one death yesterday but none since then.
He added he thought things were going well generally at what was a very busy time.
"The emergency plan went well. There's been an excellent response from staff. Seeing people injured unnecessarily is upsetting for all of us."
They are on top of the situation but it will take a lot of effort to get things back to normal in the hospital.
Chris Eakin : Tavistock Square : 1315 BST
There are people here desperately trying to find missing people, with families struggling to get information.
The cordon here is being increased in size in order to prevent people from seeing the forensic examination of the bus.
We understand the bus is about to be removed.
Gordon Corera : Television Centre : 12:55BST
The language used is that there is no direct evidence of a suicide bomber but the police weren't ruling it out. It looks increasingly like the bombs on the tube were detonated by timer but that's not definite yet. It is speculated that around 10 pounds of explosive was used. Someone could take that onto the tube in a package without looking too obvious. It isn't a huge amount but in a confined area the impact is devastating.
There is confusion about the bomb on the bus. It could have been a suicide bomber or it could have been a package that was intended to go off somewhere else. The police are trying to dampen down any speculation.
There is now going to be a huge police investigation within the UK and internationally to hunt these people down as soon as possible.
Dominic Casciani : East London Mosque : 1250 BST
Muslims around the UK are gathering for Friday prayers, the high point of the week, where communities get together to discuss events.
At the East London Mosque, closest to the scene of the Aldgate bomb, they are expecting a congregation of 7000 people.
The Imam (prayer leader) will deliver a sermon aimed at emphasising hope, peace and community resilience.
The only way to defeat fascism will be for communities to unite, he will say.
But the mosque's chairman Muhammad Abdul Bari says members of the community are fearful and he himself has received a number of hate emails.
"Muslims should not lower their heads," he said.
"We must use knowledge to ensure that others understand what Islam truly means. Terrorism has no religion."
Claire Heald : King's Cross : 1245 BST
People have already come to King's Cross with the sole purpose of laying flowers above the spot where the bomb went off below ground. There are maybe a couple of dozen bunches which have been pushed through the railings, just outside the entrance to the tube.
Joe Millard, a 20-year-old journalism student at Wolverhampton, placed his bunch of white stocks alongside the rest.
He says he was delayed from returning home to Dover yesterday by the blasts but says he had to come today.
" I come through this station a lot and I just wanted to leave flowers here to express my sadness.
"I have family living in London. I know Londoners will want to get through it in fine style as they have done and as they will continue to do."
Adam Brimelow : Television Centre : 1215 BST
The breakdown of casualties: More than 50 people were killed and police expect that number to rise. Overall there were 700 casualties and about half of those were treated for minor injuries and people were treated at the scene. 350 people were taken to hospital and about 100 have spent the night in hospital. 22 people were in a critical condition and one person has died in hospital.
Update on hospitals: The Royal Free in North London has 13 patients, Royal London in Whitechapel has 26 patients; 7 are in intensive care. Guys and St. Thomas' hospital has 12 patients, St Mary's in Paddington has 24 and University College Hospital has 27 patients and 4 of those are still in intensive care.
Jonathan Marcus : Bush House: 1155 BST
We'll see a lot of language on terrorism in the G8 summit. There is a huge amount of sympathy for Mr Blair and for the British people from the other G8 leaders. Many of them have suffered similar episodes in their own countries. And many of them have strong domestic political reasons or want to be standing four-square on this wider struggle in the war on terror.
But terrorism will be framed in a broader context because of these London bombings. Terrorism effects anyone from anywhere so the leaders will see there has to be progress on development and other issues in the summit.
Chris Eakin : Tavistock Square : 1145BST
It's the bus bombing about which there's been speculation regarding a suicide bomber. The police are holding to the line that there's nothing to suggest it was a suicide bombing. But they have also made clear there's nothing to rule it out at this stage either. The speculation has stemmed from an eyewitness who said he saw a man in an agitated state constantly bending down to a bag.
There's a great sensitivity regarding suicide bombing because it has never happened in the UK before and it will carry with it a dreadful fear.
But there has been a dearth of information coming out of this particular scene. For hours we all knew two people died on that bus. Doctors who ran down to help lost two people in that courtyard. However, it was the general belief that more must have died on that bus, though that was never confirmed.
The investigation continues at King's Cross
We know now the overall fatality figures have risen, and I think there is little doubt now that some of those will have been on board that bus.
Chris Eakin : Tavistock Square : 1038BST
There is a great sensitivity about this one particular scene.
Great screens have been put up to stop people seeing the remains of the bus, but many of the crashed cars are still around the scene.
There is a combination here of a forensic sweep and also having to deal with the grisly fact that there are human remains still here at the site.
These two things are happening together, and they are inevitably slowing each other up.
Claire Heald : King's Cross : 1030BST
The morning after the bomb underneath King's Cross and you can feel the deep rumble of tube trains moving far below the pavement. The street is steeped with reporters as it is with people now walking to work or leaving suburban trains.
Some, like Mark Margolis, who was hurt in the bomb, have come back to try to face the tube journey and regain some normality. Reporters swarm around any survivor.
Mark's message is that it would be wrong to rush to blame anyone or any group for the bombing.
Yesterday he checked himself for injuries after the blast blew out the windows of his tube carriage. He clambered out of the train, fearing the risk of fire above all.
Today he wants to travel again because his fear is that the longer he leaves it, the worse confronting it will become.
Julia Botfield : In the air over London : 1020BST
The roads are much less busy than they would usually be.
People are heeding the police warning that people shouldn't travel in unless it's absolutely necessary.
The traffic is travelling fairly smoothly across the usually busy Tower Bridge.
The river buses have been in action, but they're nowhere busy as they were last night. The terminal where hundreds of people were queuing last night is practically empty.
At Canary Wharf, very few people are in the piazzas and there is a sense of it being much less busy than normal.
Brian Wheeler : On the Northern Line: 0930BST
My Northern Line train was stuck in a tunnel for 40 minutes. Londoners are used to these kinds of delays. But there was a slight air of tension in the carriage. There were a few worried looks when announcements were made by the driver who
was doing his best to sound re-assuring. Eventually the train inched slowly into Mornington Crescent but only partially came into the station. We were asked to move to another carriage to leave the train so we could wait for another one to come along. Half the people elected to leave the station at this point.
Hundreds of walking wounded were treated
People were generally calm about it. The platforms on the Northern Line were less crowded than usual. But I couldn't get a seat on the train. I finally made it to work half an hour later than normal.
Rob Watson : Bush House: 0915 BST
According to government officials yesterday's bombings were a shock and a surprise because there was an element of chaos at first. I know because I was I was there and I saw it. I think they are pleased their training had paid off. And the emergency services coped remarkably well which is one reason they think there was less panic than there might have been.
There will be a special Cobra meeting today. This is a special collection of senior government officials, defence and military officials, security and police. They will look at how the search is going and how emergency services and transport are dealing with the crisis.
Ben Davies : Westminster : 0855 BST
The usual City-bound queue of Porsches and other prestige marques is absent in Westminster. Normally they head along the river passing through Parliament Square from homes in the west of town. The pavements are also curiously quiet - normally in this part of London they are teeming with civil servants on their way into work.
Outside Parliament the situation seems much as normal apart from the lack of people and the sight of two police officers both armed with sub-machine guns patrolling along the road.
The sirens of emergency vehicles that seemed constant on Thursday are now only periodic as the capital attempts to return to normal after the outrage.
Gill Farrington : Liverpool Street Station : 0835 BST
In the past hour, it's become considerably busy here. If you were a visitor you would think everything is relatively normal. There are people coming up on the escalators, waiting for buses and walking with their briefcases.
There are three policemen on horses and lots of British Transport Police who are on the concourse. There has been a bit of grim-faced determination from people. I've spoken to several office workers this morning. People just want to get on with it. But it is quiet and people are saying that if they've come in early and want to go home early too.
Frank Gardner : BBC Television Centre : 0825BST
One of the things being looked at is this claim published on the internet by this little known group Organisation for al-Qaeda Jihad Secret Organisation in Europe. The methodology and sheer brutality of this does point to al-Qaeda as there aren't many other groups who hate ordinary citizens in this country as much as al-Qaeda. It would fit into their pattern of revenge. They see it as a kind of retaliation for us sending our forces into Muslim lands.
We're into a terrifying second generation of al-Qaeda where there aren't necessarily links you can trace back to the leadership in Pakistan and Afghanistan.
All intelligence agencies will be activating every resource, human and technical.
They can't watch and listen to everybody and can't get it right every time, and in the end it was a failure of intelligence.
Paul Welsh : University College Hospital : 0812BST
More than 100 people were kept in various hospitals overnight - of those it seems 17 are still critically ill this morning, with more in intensive care in a serious condition. For them this morning is the first day of what could be a long and painful road to recovery.
Staff here say emergency plans worked well, but they are upset for those affected and angry at what happened.
The hospital has been quiet about how things were overnight, but we know that Accident and Emergency was quieter than it would be on an ordinary weekday night. People presumably did as they were asked and didn't go there unless they absolutely needed to.
Bill Turnbull : King's Cross station : 0745BST
Underground in difficult and perhaps dangerous circumstances a police investigation is continuing to look for clues as to what happened yesterday.
How do the police catch up with the people who perpetrated these atrocities?
Two people are known to have died on the bombed bus
But people are going back to work and there's this extraordinary hustle and bustle.
This feels like one of the safest places in the country to be - there are so many police officers around. I just saw a police officer with a sniffer dog checking cars and other spots in the station.
But the day goes on.
Neville Dalton : Travelling from Haywards Heath : 0700BST
The Brighton-to-London Victoria train that collected me and dozens of fellow passengers at Haywards Heath, in West Sussex, had spare seats. Loads of them. Maybe some people just couldn't face the prospect of journeying through the capital so soon after hundreds of their fellow commuters were killed or injured in an attack that you just couldn't prepare for. Perhaps some of them were genuinely scared?
But surely it wasn't just the fact that there were fewer of us that accounted for the almost eerie silence on the 50-minute journey into Victoria? People studied the morning papers and saw grim pictures of people just like themselves staring back at them. The silence was almost a respectful one. The normal breezy chatter of passengers using their mobile phones was conspicuous by its absence.
But the real difference was the attitude to security. Commuters are used to signs and messages reminding us to take our belongings with us, but what we're not used to is a railway security officer walking up and down the aisles, checking that each bag belonged to someone on board. It may have been unusual, but it was somehow comforting.
More evidence of change came at Victoria station, where transport police almost outnumbered passengers. And there were spare seats on the Victoria Line trains.
This really was a different day.