Police had identified two of the suspected bombers arrested Friday as Muktar Said Ibrahim and Ramzi Mohammed. A Scotland Yard official, speaking without attribution under police rules, said a man arrested Friday in west London was called Wahbi Mohammed, 23, and may have been a fifth bomber. The official said he was possibly a brother of Ramzi Mohammed.
The capture of four men in the July 21 attacks, and of another in a possible fifth attack the same day that was apparently aborted, brought only the most cautious sense of relief to Britons, and police warned that the country still faced what Peter Clarke, London's top counterterrorism official, called a "very real" threat.
"The public must be watchful and alert," he said Friday.
Indeed, that seemed to reflect the mood among many Londoners on a day when their newspapers feted the capture of the suspected bombers with banner headlines like those in the Daily Express, "Thank God," and The Daily Mirror, "Got Them."
Riding a packed Victoria Line subway train yesterday from Finsbury Park to Stockwell, where the failed attacks began, Natasha Snell, 22, a dental nurse, said: "I think there's more people out there waiting to do it. It doesn't make it any less anxious. I said to my friend this morning as we were coming into the station, we'll go to the end of the train because it always happens at the front."
The Los Angeles Times is a Tribune Publishing newspaper. The New York Times News Service contributed to this article.