THE ATTACK:
Three bombs exploded almost simultaneously around 8.50am on three packed Underground trains in north, east and west London. A fourth bomb ripped through a bus less than an hour later.

Each device weighed less than 4.5kg and was packed with high explosives.

The bombs on the Underground were likely left on the floor of a carriage by a double door, which would have typically been filled with rush hour commuters. The fourth bomb on the bus was likely left on the floor or on a seat.