Police Issue Bomb Suspect Images
Police have issued CCTV images of four men they want to question over the attempted bomb attacks on three Tube trains and a bus in London on Thursday.
Met Assistant Commissioner Andy Hayman said anyone who knew who or where the men were should contact police.
The bombers fled after detonators went off that failed to ignite explosives.
A man shot dead by anti-terror police at Stockwell Tube on Friday was not one of the four suspects. Investigations later led to the arrest of a man.
The man was detained at about 1715 BST in Stockwell, south London.
Metropolitan Police Commissioner Sir Ian Blair earlier told a news conference that the fatal Tube station shooting was part of anti-terrorist operations.
Scotland Yard urged anyone who knew the whereabouts of the men captured by CCTV to call 999, or if they could identify any of them to call the anti-terrorist hotline on 0800 789 321.
Officers raided three addresses across the capital on Friday as part of anti-terrorist operations.
That included a search of an address in Harrow Road, west London, where area resident Patricia Osbourne said she heard six shots fired.
Sir Ian told a news conference on Friday that Scotland Yard was facing "the greatest operational challenge" in its history.
Officers hunting Thursday's would-be bombers were facing "previously unknown threats and great danger", he said.
"This operation is targeted against criminals - not any community or section of a community," Sir Ian added.
Thursday's attacks began at about 1230 BST, with bombs at Warren Street station, central London, Shepherd's Bush station in the west, Oval in the south and on a bus in Shoreditch, east London.
Along with the CCTV images, police revealed details they believed about the suspects' movements:
- The first image showed a man in a black sweater running away from Oval station's Northern Line at 1234 BST on Thursday. Police believe he had travelled north from Stockwell. His top was later found in nearby Brixton.
- The second image showed a man on the number 26 bus travelling from Waterloo to Hackney Wick. He got off the bus at Hackney Road at about 1306 BST.
- The third image showed a man leaving Warren Street station at 1239 BST.
- Police believe the man pictured at Westbourne Park station at 1221 BST travelled west on the Hammersmith and City Line to Shepherd's Bush, where he ran from the station.
Following the incidents, streets were cordoned off, parts of the transport network closed and stations evacuated, but no-one was badly hurt.
Two men, one arrested in Whitehall, close to Downing Street, and another around Tottenham Court Road, were later released without charge.
Three of the devices found were the same size and weight as those used for the 7 July London bombings, while the fourth was smaller and appeared to have been contained in a plastic box. The same chemicals appear to have been used.
Assistant Commissioner Hayman told the news conference: "At this stage it is believed the devices consisted of homemade explosives and were contained in dark coloured bags or rucksacks. It is too early to tell how these were detonated."
Sir Ian said on Thursday: "Clearly the intention must have been to kill. You don't do this with any other intention."
Former government intelligence analyst Crispin Black said the chance to examine the bombs themselves was "forensic bingo", saying: "This is as good as it gets."
BBC security correspondent Gordon Corera told BBC Radio 4's Today programme the devices were so similar there was speculation they could have been part of the same batch.
"The explosive might have degraded over time or had not been put together right in this case, or it could have been a completely different batch of explosives - homemade - that had not been cooked up properly."
The bombers' plan might have been disrupted by the investigation into the 7 July attacks, forcing them to act before they had been fully prepared, Corera added.
Some witnesses said the Thursday's attackers seemed "scared" or "surprised" when their bombs failed to explode properly.