Plainclothes police chased a man in a thick coat through a subway station, wrestled him to the floor of a train car and shot him to death in front of stunned commuters Friday. Police said the shooting was "directly linked" to the investigations of the bomb attacks on London's transit system.
Later Friday, police announced two arrests, saying one was connected to Thursday's attacks. A man was arrested in the south London neighborhood of Stockwell – the same area where the shooting occurred – and detectives were searching a premises there, a police statement said.
In Birmingham, anti-terror police arrested a man at rail station and seized at least two suitcases. The Snow Hill rail station in Birmingham, 110 miles northwest of London, was evacuated and cordoned off, police spokesman Will Harpur. It was unclear whether the arrest was connected to Thursday's attacks.
Appealing for help from the public to capture the suspects, police released photographs of four men suspected of launching Thursday's second wave of terrorist attacks, saying they bore similarities to the July 7 bombings that claimed 56 lives.
Thursday's bombs partly detonated and contained homemade explosives, police said.
The photos, taken from closed-circuit TV cameras, showed one man wearing a dark shirt with "New York" across the front running through a subway station. Another was shown on the upper level of a double-decker bus, while the other two men were shown at separate subway stations.
The man who was slain by officers at the Stockwell subway station around 10 a.m. "was challenged and refused to obey police instructions," Police Commissioner Ian Blair said.
"This shooting is directly linked to the ongoing and expanding anti-terrorist operation," Blair said.'
The dead man was not believed to be one of the bombers, but linked to them in some way, said CBS News Reporter Larry Miller.
Passengers at the Stockwell station said a man, described as South Asian, ran onto a train and was chased by plainclothes police. The man tripped, and police then shot him multiple times.
"They pushed him onto the floor and unloaded five shots into him. He's dead," witness Mark Whitby told the British Broadcasting Corp. "He looked like a cornered fox. He looked petrified."
Another witnesses, Anthony Larkin, told the BBC that the man appeared to have "a bomb belt and wires coming out."
Police shouted "Get down, get down!" he said, adding that "People were panicking and I heard shots being fired."
Whitby, however, said the man did not appear to have been carrying anything but said he was wearing a thick coat that looked padded. Temperatures in overcast London on Friday were in the 70s.
Elsewhere in London, detectives investigating Thursday's explosions searched a building in the Harrow Road area of West Kilburn, although no arrests were made, Scotland Yard said.
Police reportedly told residents to get inside their houses and then brought in a bomb disposal unit, including a remote vehicle, witnesses said.
Also Friday, police evacuated one of London's largest mosques after a bomb threat before Friday afternoon prayers.
"Someone phoned our director and said there was a bomb inside," said Mohammed Abdul Bari, chairman of the East London Mosque.
The Metropolitan Police lifted the cordon about an hour later, saying no armed officers were involved, and the incident appeared unrelated to the subway shooting.
More than 6,000 people were expected for Friday afternoon prayers but there were only about a dozen people inside at the time the threat was telephoned in.
Meanwhile, a statement posted Friday on an Islamic Web site in the name of an al-Qaeda-linked group claimed responsibility for Thursday's attacks. The group, Abu Hafs al Masri Brigade, also claimed responsibility for the July 7 bombings. The statement's authenticity could not immediately be verified.
Jittery commuters already facing cutbacks in service from the last attack faced more Underground closures Friday.
"People are worried, but if it's going to happen, it's going to happen, isn't it?" said Chidi O'Hanekwu, 23. Still, he said he found himself being "a bit more paranoid" on the ride in.
Mia Clarkson, 24, defiantly said she refused to change her schedule. "You've got to keep living, don't you?" she said as she exited the Chancery Lane station after a trip from across town.
Newspapers reflected the city's volatile mood — part defiance, part anxiety.
"Britain will not be beaten," vowed a front-page headline in the Daily Express. "Is this how we must now live?" asked the Daily Mirror over pictures of the attacks' aftermath. The Independent had a similar photo montage and the words: "City of Fear."
"There are some reports that the bombs were almost identical or maybe identical to the bombs that exploded two weeks ago. Whatever happened, however, these were not made as well, and it's a great stroke of good luck that three of the devices didn't go off, even though the detonators did, and that in the other device that they had a bad detonator. That didn't happen the first time around with grave consequences."
Jeremy Binnie, an analyst with the London-based Jane's Terrorism and Insurgency Center, said Thursday's attacks seemed "much more amateurish in many ways" than the earlier one.