Here is a selection of accounts we received from eyewitnesses at the scene of the bus explosion at Tavistock Square.
I was just a few yards away from the front of the bus.
Stephen Thornhill took this picture just after the bus exploded...
The driver had called across to the policeman to ask the place name as he was clearly off route and the back of the bus just exploded up and out to the rear.
The roof lifted lazily forward and a long length of metal spun up twisting in the air.
As I realised the blast was coming I rushed away and was hit by the hot blast and debris.
Luckily for myself and another pedestrian a small builder's van prevented much of the flying material from hitting us.
I looked back and was hugely glad to see an amazing sight - many people just stood up on the upper deck.
I could not believe that so many, so close were seemingly unhurt.
...and another of its aftermath
I am sure that they were not alright.
It was almost surreal to see the upper deck cut off at that low level and so many passengers were still alive.
At least two people were helped away from the scene covered with much blood and many more behind.
I am a doctor and was one of the very first people on to the scene of the bus explosion.
The carnage was devastating and the image will stay with me forever.
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 terrorise us are in vain.
I saw this bus literally just explode.
There was a huge noise and there were bits of glass flying everywhere.
I couldn't get too close because the police were on the scene immediately.
They cordoned off the area and were getting rid of people.
But I did see a bus driver in a complete state of shock being led away by a policeman and there were two ladies with bits of blood in their hair and glass.
So I took the two ladies away and just tried to find them somewhere to sit down.
The atmosphere along Euston Road this morning was very different to most.
The pavements were packed with confused tube travellers and the roads gridlocked.
I was surprised to see that the police were even preventing pedestrians walking down towards Kings Cross (the direction I wanted to go).
I tried to establish what was going on but the police were busy enough and so spoke to another pedestrian who confirmed that we could not go any further.
So I was re-directed down Tavistock Street when a minute or so later I heard an explosion and saw a huge piece of red metal and lots of debris propelled high into the air in front of me.
Later I deduced this must have been the roof of the bus.
People, including myself, seemed to remain fairly calm to begin with but later when I heard reports from other pedestrians about what they had seen I began to get quite emotional.
It's an odd feeling being so close to such a horrific incident. If I hadn't stopped to find out about the detour then I dread to think how close to the blast I would have been.
Perhaps even stranger was the feeling of being completely vulnerable and utterly trapped within London's vastness. I didn't know where to turn to and my mobile not working didn't help.
My heart goes out to all those innocent people involved in the blast and to all their relatives and friends.
I reached Euston station by Silverlink county close to 0900, and walked to Euston Square tube to find police blocking it.
So I went back to Euston station again to access the underground.
I am lucky to be writing this. This was the first time I smelt death so near.
The police were evacuating there too, saying there was a possible explosion at Liverpool Street.
So then I took the number 59 bus to reach Holborn.
As the bus passed a bit after Tavistock Square park, we heard an explosion - something like a big bang, sort of muffled inside a metal container.
We looked back from the upper deck and saw a huge metal scrap thing on the road, with a few fumes coming out. Someone was on the road trying to pull something out of it.
All of us panicked and hurried to get out of the bus. People were losing it completely.
I am lucky to be writing this.
This was the first time I smelt death so near.