In the confusion of the immediate aftermath of the 7 July bombings, readers' e-mails and photos to the BBC News website helped tell the developing story.
Alexander Chadwick took this picture in the tunnel at King's Cross
As the day progressed, they sent hundreds of e-mails detailing their experiences, often in graphic detail, and their emotions. Here is a selection:
"Apparently there has just been an explosion at Kings Cross and people are screaming and running about."
Karla (0955 BST)
"There are many fire engines and ambulances rushing past the window of my building. There is a lot of people phoning loved ones to make sure they are ok. Feels a bit like September 11th all over again here."
Amy Hinkley, London (0957)
"I was at Liverpool Street station at the time of the 'bang' at 8.49 and had just got off the Circle Line when it happened. The lights in the station went out and my friend told me to duck down. We are both ok now but even now I am still shaken up. I am now at work in Holborn and can hear all the emergency services out and about. It is completely scary."
Louise Pope, London (0957)
"I have just managed to travel into work via taxi having seen people injured and looking dazed on the tube. It's mayhem and no-one knows what is going on - rumours are already abound of terrorist attack and deaths. The sooner an announcement is made the better."
Jolyon Segal, London (0957)
"My gf works up by holborn and has just called to tell me a bus has exploded outside her office in tavistock square, bodies strewn all over the road etc."
Andrew McCormack (0958)
"I work just up the road from Aldgate\Aldgate East. Someone has just arrived in the office who claimed to be on the tube train that was involved. He was on the Metropolitan line coming into Aldgate, there was a loud bang and a large flash, the train stopped and the lights went out.
Smoke started coming into the carriage and people were screaming. After about 10 minutes they were led out of the front of the train and along the track to Aldgate, he said there was a carriage that had been 'ripped apart like a tin can' and he could see people laying inside, a door from the carriage was laying on the track, there were several people bleeding with head injuries. He finally made his way up to the station and out from there.
Another person arrived earlier said he saw people lying outside Aldgate station covered in blood. There's loads of noise outside from sirens and helicopters overhead"
Peter Fuller, London (0958)
"I work around Aldgate station and the whole area has been cordoned off. There are police and fire trucks everywhere, with people stuck on buses. Saw at least 5 people injured; particularly one with blood running from his ears. It was a terrible, terrible scene."
Sola Akinloye, London (0958)
"Just walked past Edgware Rd Station and people were saying they heard a mini-explosion and someone was caught under the train yelling for help. Was not given much more info."
Diyan Danikumar, London (0959)
"I was in the back carriage when we heard a loud bang and the lights went out. We sat in the dark for 20 minutes joking that it was probably a derailment until we were ushered out of the back by LUL staff. We walked past a carriage with a hole in the side and three people lying on the rails; not sure of their condition. Outside the emergency services ushered us away."
Andrew, Aylesbury (1004)
14 people, including the bomber, died at Tavistock Square
"My son has just phoned to say his partner was on a bus stuck in the traffic chaos - as it wasn't going anywhere she got off and walked up the road a bit - the bus then exploded and she was thrown to the ground. She's lucky to be alive he says."
Peter Nicholls, Melbourne, Australia (1019)
"I was on the next carriage down from the blast at Aldgate. I saw bodies on the track, one was moving, the other two I'm unsure of. terrible scenes. the whole carriage was ripped out. extremely shaken up."
Scott, Hornchurch (1022)
"I was on Eastbound Circle Line Train when the explosion occurred in the train opposite in the tunnel. That train was severely damaged and our train was fine. We soon started hearing screams form the other train and our train started to fill with smoke. Most people, though worried, remained calm and we were then evacuated via the front of the train."
Gareth Evans, UK (1053)
"I am a doctor and was one of the very first people on to the scene of the Woburn Street bus explosion. The carnage was devastating and the image will stay with me forever. The smell of burning flesh was overwhelming. I counted at least 4 dead bodies.
Once I overcame my initial shock, I started trying to help the survivors along with the few other members of public there. Once the paramedics arrived, we had medical supplies available to patch people up as best as we could before they were rushed to hospital.
This has been the most horrific experience of my life and hope I never ever see anything like this again. I do not understand how the murderers responsible for these atrocities can justify them in the name of their God. We must get London going again so that their attempts to terrorize us are in vain."
Julia Phillips, London (1840)