101 days after the 7 July London attacks, which killed 52 people and injured 700, two survivors and a paramedic gave the BBC's security correspondent Frank Gardner on Radio 4's Broadcasting House frank and graphic accounts of their experiences.
Survivor Gill Hicks
I was fighting against blacking out - knowing that if I did that I wouldn't come out from that.
If anyone thinks they've heard screaming before they've never heard that kind of screaming. That was the screaming of seriously injured dying people.
Paramedic Craig Cassidy
I had to make the choice that nothing could be done for him and he had to be left.
GILL HICKS - Kings Cross Tube survivor
We'd just pulled out of King's Cross Station. It couldn't have been more than a minute or so and it was just like someone had flicked a switch.
It was like being transported from a sunny day on a beach to suddenly being on top of a mountain and snow - it's that bizarre and that extreme.
And you don't know how you made the journey and actually you don't care.
All you know is you're in a different place.
All I felt was that I was just sinking, and sinking in just very thick black liquid, that's just how physically it felt. And sounds were very, very muffled.
It wasn't until I realised that I couldn't breathe and opened my eyes a bit that the screams became more prominent and we were all transported into a different environment and I wasn't alone.
It was just so surreal. There were frantic screams but then very quickly those screams start to reveal silence and you're left with a few people screaming. And then silence.
So it's very eerie.
I asked someone to help me stand because I was on the ground and whoever that person was somehow managed to get me to a bench seat.
And it was only at that time that due to an emergency light in the tunnel I could see what had happened to me and my legs.
It literally was like looking at an anatomy picture of the inside of the human body, and surprisingly I was incredibly calm.
Both my feet were almost surgically severed - so they were still hanging on to what remained of my legs, but my legs basically were just two bones sticking out from some interesting mess above them.
It was about half an hour before I saw a flashlight, so what I'd done in the meantime was realised I was losing so much blood.
It was the very rare occasion that I had a scarf on, so I took my scarf off and I tied a piece of the scarf around each leg
I knew I had to elevate my legs, so I had to try to lift them somehow and lift them over the arm rests of the bench seat and hang on.
There was nobody around. There were people talking across from me - people trying to calm each other - but I felt that my experience was quite lonely.
It feels like there was lots of lonely individuals in one setting. I was fighting against blacking out - knowing that if I did that I wouldn't come out from that.
It was a dialogue in my head, of the body just saying: 'Rest - go to sleep close your eyes - that's a much better plan - everything will be all right - someone will come and find you and it will all be nice and calm. Just close your eyes.'
And the other half saying: 'If you close your eyes Gill you won't ever open your eyes again - so don't listen to that, keep your eyes open and watch for a torch.'
I think the most amount of panic I ever felt was suddenly - does anyone know we're down here?
Rather than praying I think what I was having was a direct conversation with God - almost - and I really believe that once I made the decision to stop this dialogue of 'go to sleep and stay awake' - I made a very conscious decision.
I looked around the carriage and I just suddenly said to myself: 'I'm not going to die down here. This is not the end for me - this is not where Gill Hicks dies.'
I have very patchy memories about the first few days - waking up in intensive care - but due to having a life support and having tubes in, I remember motioning to the nursing staff or gesturing 'what's happened to my legs?' because I clearly remember seeing the vision of this anatomy picture, if you like, in the Tube and wondering what had happened.
They then told me - which was a very brave decision I think - that my legs were indeed amputated.
I was very distraught.
I'm extremely positive - but I'll be real in saying there's not a day that goes by that I don't mourn my limbs and the use of my limbs because I can only wear my prosthetic legs maybe two hours one day and three the next.
So it's what you do in the middle bits. That's a wheelchair and crawling like a baby - and those things if you've got a sense of humour can be hilarious. But I think the laughing is definitely on the outside.
The real situation is its horrible. Of course it's horrible - it's devastating.
The only way I cope is to say there was my old life and now this is a new life and I hope to God that I can make sense of it and do something with it.
I feel the overwhelming euphoria of being alive - and maybe that's a sense of cheating death, or being saved. There or lots of these things that are rolled into that. How wonderful that I'm here.
But then of course that is clouded by the fact that I can't walk.
I think I scared the priest that's going to marry us (my fiance and I).
He came to see me in intensive care - four days after I'd been admitted.
Apparently the first thing I did was bolt straight up in bed and say: 'I'm going to be walking up the aisle!'
That's been fantastic date to focus on - and a reason to walk - it's now only part - I want to walk because I want to try and have some sort of life back.
I'm desperate to have my life back.
Listening to hear other survivors talk, I'm so relieved that we seem to have a common sense that we don't have any anger toward the bombers.
I personally feel very sad and have a great deal of pity that their families are incapable of grieving publicly, and also that these young men have been susceptible to a message and have taken their own lives to what I see is very much in vain.
I view them as victims and that also helps me feel very sad for them.
IAN - Bomb survivor
I remember thinking that I've never been on such a packed train.
The next thing I remember was reading a paper and then getting a sharp feeling of electrocution, like I imagine anyone who has been struck by lightning gets.
I was knocked unconscious either during or after the electrocution and I maybe came round about 10 minutes afterwards.
I couldn't see anything or feel anything or hear anything. The instinct when that happens is to assume that you're dead and this was some kind of spirit world that you are now in.
There were body parts everywhere. There were arms, there were legs, there were limbs and there was blood and there was huge amounts of screaming.
If anyone thinks they've heard screaming before they've never heard that kind of screaming. This was the screaming of seriously injured dying people. It was an unnatural screaming sound.
This was the screaming of seriously injured, dying people.
There was no panic because you were still alive and there was still that relief to be alive because you knew that other people weren't alive at this stage.
But I remember thinking I needed to try to stand up.
But when I looked down to see what was on my legs I realised there was just a body on top of me, half a body, a dying body and I was putting my hand on a dying body.
And I had to, with my two arms that still worked, move that body away from me to feel if I still had any legs any more and I tried to walk.
But every time you put your foot anywhere and every time you put your hand anywhere, you seemed to be treading on human flesh or a body.
Your humanity strikes in, you think is there anyone you can save here or take out with me?
A right hand came out and held onto my leg and I tried to see where they were and you couldn't see anything. It was just a mass of bodies and I thought instinctively I've got to get that person out.
There was another guy to my right who was just frozen into his seat, eyes wide open, mouth wide open. This young guy just absolutely frozen and I remember going up to him and shaking him and saying 'You've got to get out' and trying to carry him out.
But people are very heavy and he couldn't be moved - he was in absolute shock.
I did try and pull the hand out of that person and you just couldn't see anything and there was just body on top of body and they were so heavy.
I've had odd dreams about it. I've had dreams about being in a Tube train with a suicide bomber.
I didn't use the Tube for two and a half months and then I thought it would be interesting thing to see if I could do it or not.
Last week I had a go and I did the journey I did that day.
I went through the tunnel where it happened and to Russell Square where I lay injured for two or three hours waiting for an ambulance to arrive. Because I had some ghosts that I wanted to lay, I had some demons.
Have I purged those demons at Russell Square? Absolutely not.
I went to work on 7 July and I came within one yard of never living again. That's part of me now and I just try to take that in the most positive way I can.
The one thing it's done is show the best of humanity and the worst of humanity on that day.
What springs to mind is not the worst of humanity because anyone who straps explosive to themselves to blow people up is a murderer.
What people did to save people and taking off their coats for people to use them as blankets and running to the shops to get people water - that was the best of humanity.
There were people from the Tube that day and there were people that came in from the outside and there were people who were walking by who were heroes that day in every sense of the word.
CRAIG CASSIDY - Paramedic
It was dark, it was eerily quiet, apart from some phones buzzing and a few people crying out quietly. It was quite calm - but it was like a scene from hell certainly - yes.
In the carriage there were four people to my left-hand side.
One person - a female who was obviously dead - was being held up by another patient - who had no real injuries but who stayed behind to hold her up because she thought she could help her.
Looking further down the train on the left-hand side was a pile of the deceased, with various injuries.
And looking towards the end of the carriage, where the explosion had obviously taken place, I could see a bunch of firemen and about four or five other live casualties - and about three or four five bodies - or remains of bodies.
One person on the floor - I believe was a male - unfortunately was trying to get up off the floor, but had lost one of his arms and both legs. The part of the brain that always tries to fight for you was trying to get him off the floor to save him.
I had to make the split decision that he had to be left.
If he'd been the only patient we could've done something for him but with too many people there we.. I had to make the choice that nothing could be done for him and he had to be left.
Because we have to look after the people who could be saved, not the people who are too severely injured and that will take up too much time.....
...that person I still constantly think about. Should I have gone to that person immediately? I know deep down that I did the right thing not doing that, because I had to save the most for the most, but I can't forget that person.