Inspector Stephen Mingay was the first police officer to reach the blast-hit Tube train at King's Cross underground when the bombers struck on 7 July.
Insp Mingay was praised for evacuating many passengers
He was standing at the entrance to the Piccadilly Line when he felt an explosion beneath his feet.
"I literally felt the explosion through the ground," he said after receiving an award for his "outstanding actions".
He was one of 96 British Transport Police officers praised for their rescue work after the bombings.
A few moments after the blast, he saw "soot-stained" passengers making their way out.
He described seeing a "big wall of smoke" coming up from the tunnel as he ran towards the track with a colleague.
After turning back to call 999, he returned and walked along the track for 100 metres until he reached the train.
"There were a lot of scared people in the back of that train," he said. "Some people were so scared I had to lift them off the train.
"We did not know there had been simultaneous attacks, we were unaware of the other bombs going off."
'Called for quiet'
After aiding the walking wounded, he eventually reached the carriage where the bomb had detonated.
"What I saw in that carriage - no amount of training could prepare you for that," he said.
"I called for quiet and identified myself and what I was going to do for them; to go back so as I could get the specialist help they needed."
The 46-year-old said leaving the wounded to get help was one of the hardest decisions he had faced in his career.
Although it went against his instinct, he believes his actions "enabled a more co-ordinated rescue and probably saved more lives".
He was commended for evacuating "large numbers of passengers from the bomb-damaged train amidst horrific conditions".