A Tube relief driver who should have been sitting in the bombed King's Cross carriage has described the panic and disbelief during the rescue effort.
Ray Wright should have ridden near the suicide bomber in the front carriage, but it was so packed he sat in the front cab with his colleague.
"There was an explosion, the lights went, the cab door, we believe, blew in and smoke came in," he told BBC London.
"And the screaming, that's what we remember more than anything else."
Piccadilly Line driver Mr Wright would usually have been sitting in the carriage where Germaine Lindsay, 19, is believed to have carried out the most deadly of the four attacks on 7 July - killing himself and 26 others.
But he told how he sat up front with his colleague because the carriage was packed to capacity that morning.
"We call it crush conditions, you couldn't have got any more passengers on that train," he said.
"We got about a train and a half's length into the tunnel, everything seemed okay, when all of a sudden there was an almighty explosion and I remember everything happening at once."
Back in the passenger carriage, he described a "sea of blackened faces in a state of total panic."
"We were screaming, above the shouting, for everyone to calm down, that we were okay at the front and we were going to get people off."
He said as they got people off the train, he and the driver still thought it was a mechanical or electrical fault.
It was only when the first police arrived he was told other bombs had gone off on two other Tube trains and one on a bus.
While a local hotel brought blankets to the booking hall at Russell Square, Mr Wright watched as doctors tried to resuscitate passengers - "it was evident that there were limbs missing," he said.
"It's not something you anticipate seeing when you come into work, but I think by then the emergency services were there and they were in control.
"I think at the same point we were still standing in total disbelief that this was really happening.
"I was offered counselling, I haven't found I have needed it so far but if I need it it is always there. I'm back to work next week."