LONDON- Police released photographs Friday of four men suspected of launching a second wave of terrorist attacks on London's transport system and said the attacks bore similarities to the fatal bombings on July 7.
Police said the bombs on Thursday partly detonated and contained homemade explosives. Metropolitan Police Commissioner Sir Ian Blair said the fatal shooting by officers of a man at a London subway station Friday was linked to the ongoing anti-terrorism operation.
The police photographs showed one man, wearing a dark shirt with "New York" across the front, running through a subway station. Another was shown on the top of a double-decker bus, while the other two men were shown at separate subway stations.
Blair, who is Britain's most senior police officer, told a news conference in central London that his force was facing its "greatest operational challenge ever" and that anti-terrorism officers were working around the clock.
He was speaking hours after plainclothes police chased a man through a south London subway station, wrestled him to the floor and shot him to death.