I've just been watching The Angels of Edgware Road on Channel 4:
"The Angels of Edgware Road is the second of two documentary films commemorating the third anniversary of the 7/7 London bombings. Two trains stand motionless next to each other in a tunnel just outside the Edgware Road tube station. A bomb has just exploded on one of them and the air is thick with smoke and the terrible screams of injured and dieing commuters."
It is hard to picture I know, but if you were in a situation - any situation, not necessarily a bomb on a train - would you get out as quickly as possible, or would you stay and try to help?