The device was on the floor of the second carriage, close to the forward set of double doors. It killed six people, plus the bomber, and injured 163 others.

Passenger Chris Randall told the BBC the train had just pulled out of Edgware Road "and the next thing I knew there was a large flash of light".

"On the tube there was, I would say, maybe six or seven people lying on the floor. A lot of people with a lot of blood on their faces and ripped clothes."

Another witness spoke of parts of the driver's compartment, such as the doors and the roof, lying scattered around the track.

After the blast, surivors were cared for by emergency services and volunteers in the nearby Marks and Spencer supermarket and Metropole hotel.

The oldest of the four bombers, Mohammad Sidique Khan, 30, was named by police as the man who set off the bomb.