British police say they believe the suspects in last week's failed bomb attacks on the London subway and a bus are still in the city and may try to strike again.
Police Monday named two of them, 24-year old Yasin Hassan Omar, and 27-year old Muktar Said Ibrahim, also known as Muktar Mohammed Said.
Security camera pictures of all four have been flashed on British television.
The suspects fled when their bombs failed to go off on July 21st in three subway stations and a bus.
Police say a fifth man who apparently left a bomb in a London park, may also be on the loose.
Also Monday, Prime Minister Tony Blair said Britain is "desperately sorry" for the police killing of a Brazilian man mistaken for a terrorist.
Police shot Jean Charles de Menezes in a subway station last Friday when he failed to obey their command to stop running.
Brazilian Foreign Minister Celso Amorim said in London Monday that fighting terrorism must include respect for human rights.
Some information for this report provided by AP, Reuters.