Four suicide bombers, at least three of them British, were responsible for the explosions that killed more than 50 people in London, senior security sources said last night.
The three were all thought to be of Pakistani ethnic origin and said by neighbours to have lived modest suburban lives in West Yorkshire.
Police stand guard over a house in Colwyn Road, Beeston, as a forensic officer removes evidence
One has yet to be identified, while the others were not known to police or the intelligence services as terrorist suspects.
One was the son of a fish and chip shop owner. Another was only 18 years old and was reported missing by his worried parents at 10pm on the day of the bombings.
Police said the bombers made a rendezvous somewhere outside London last Thursday morning, travelled together to King's Cross Thameslink station wearing large military-style rucksacks containing 10lb high-explosive bombs and split up to attack their assigned targets.