Police suspect 4 Britons carried out suicide blasts

LONDON -- In a chilling breakthrough in the investigation into last Thursday's deadly train and bus bombings, police officials said yesterday that they have evidence indicating four British citizens of Pakistani descent carried out what now appear to be the first suicide bombings in Western Europe.

News shakes Muslims in suspects' home city. A10.

Initially, police suspected the culprits had placed the bombs in bags on the floors of three crowded morning rush-hour trains and got off, leaving them to explode, as did the Islamic radicals who bombed commuter trains in Madrid last year, killing 191 people. Police had thought the bus bomb may have exploded by accident.

But yesterday British police said their investigation suggested a more alarming scenario -- that for the first time in Western Europe, Islamic extremists had carried out a suicide attack. Police officials involved in the investigation, speaking on condition of anonymity, said they believe the bombers were British nationals, three of them from Leeds, a city 200 miles north of London, who traveled to the capital by train and linked up with a fourth man at Luton, just north of London, before launching the attacks that claimed at least 52 lives and left more than 700 wounded.

Police did not disclose the identities of the four men. The police officials said privately that the suspects were not known to police as Islamic extremists, fitting the profile of ''sleepers" who were chosen for the mission because they had not previously attracted police attention.

Early yesterday, police raided six homes in and around Leeds. Police evacuated about 600 residents in the neighborhood and said they found explosives in at least one home.

Conscious that the Madrid bombers blew themselves up last year when cornered, killing a Spanish police officer, British police sent in a radio-controlled robot to search some of the residences, and in one case carried out a controlled explosion to make sure the explosives in the house would not detonate.

During the searches, police confiscated written material and computers from some homes, and one man, a relative of one of the four suspects, was arrested and taken to London for questioning at the high-security police station at Paddington Green, police said.

Police also searched a car in a rail station parking lot in Luton, 30 miles north of London, which police believe was driven there by the suspected bus bomber, who joined the other three there after they arrived from Leeds on London-bound train early Thursday morning. Fearing the car might be booby-trapped, police carried out a controlled explosion and found explosives in the car.

Police officials refused to publicly use the words ''suicide bombers" in describing the four men they believe carried out the attacks, saying they only had conclusive evidence showing one of them had died with his bomb. But privately, officials said they had forensic and physical evidence, including credit cards and other materials commonly found in wallets, indicating that all four had remained with the devices, three of which exploded within 50 seconds of each other on separate trains.

M. J. Gohel, director of a London-based counterterrorism think tank, said the idea of home-grown British suicide bombers targeting their compatriots had elevated the threat of terrorism to an unprecedented level.

''We are now in an entirely new dimension as regard the terror threat," said Gohel, ''a new generation of terrorists, intelligent, educated individuals from solid middle-class backgrounds . . . possessing all the Western social skills, no criminal record . . . who fits in totally but is infected by the Al Qaeda ideology of global jihad, a hatred for the country he lives in, and the desire to destroy the democratic and secular world."

Police suspect a fourth device did not explode at 8:51 a.m. like the other bombs, either because its trigger malfunctioned or because the bomber couldn't get onto a train as planned.

They said the fourth man was among commuters who were evacuated from the Underground subway system and then boarded a double-decker bus in the Bloomsbury section of London, where he apparently triggered the bomb 57 minutes after the initial explosions.

About 12 hours after the bus blew up, the family of the suspected bomber, apparently unaware of what police believe was his involvement in the attacks, called a hotline established after the bombings to report him missing. That turned out to be a critical clue that through undisclosed means helped police to establish his identity and that of his three associates after reviewing hundreds of hours of closed-circuit camera film from train stations. That triggered a major acceleration of the investigation.

A police source described the suspects as British nationals. A European investigator told the Globe that at least two of them were of Pakistani descent.

In Leeds, an old industrial town of 715,000 with a sizable Muslim minority, the streets were quiet last night in the Hyde Park section, where the Grand Central Mosque dominates the skyline. The mosque was surrounded by police barricades, and some Muslims distanced themselves from the suspected bombers.

''If you commit suicide, the Koran says that is a coward's way of dying," said Musrat Hussain, 26, who works at GE Capital. ''I can't understand what goes on in their heads. This has nothing to do with Islam."

There was no immediate indication what kind of terrorist cell or other organization might have been operating in Leeds to generate such an attack operation.

Deputy Assistant Commissioner Peter Clarke, head of the Metropolitan Police's antiterrorism branch, told a news briefing that the four men police believe carried out the bombings were photographed by a closed-circuit camera together at King's Cross station shortly before 8:30 a.m. Thursday. Three had made the three-hour train ride down from Leeds, while the fourth had apparently joined them for the last 40 minutes of the journey from Luton.

According to a police official, speaking on condition of anonymity because of the sensitivity of the investigation, at King's Cross station the men, all carrying rucksacks, set off in separate directions, and 20 minutes later there were three explosions on trains that connect at King's Cross but were heading in different directions: east, west, and south. Police theorize that the bus bombing suspect was either frustrated in his attempt to board a Northern Line or Victoria Line train heading north, or that he got on a train but was unable to trigger the explosion.

A spokesman for London Transport confirmed that just prior to the explosions there were heavy delays on both the Northern Line and the Victoria Line, which connect through King's Cross and have north-south routes.

The police have spoken to several witnesses who said they saw an agitated man on the bus repeatedly reach into a bag prior to the explosion, and investigators now suspect the man was trying to trigger the bomb. Police say 13 people died in that blast. While police sources said the bomber was among the dead, Clarke would say only that the man's belongings were found in the wreckage.

Clarke said police had forensic evidence that one of the suspects died in a Circle Line train heading east from Liverpool Street to Aldgate. He said police also recovered items belonging to him and another suspect at the site of the Aldgate bombing.

Clarke said belongings of another suspect were found on a Circle Line train that exploded while heading west toward Edgware Road.

''We are trying to establish their movements in the run up to last week's attacks, and specifically to establish if they all died in the explosions," he said. ''We have since found personal documents bearing the names of three of those four men close to the seats of three of the explosions."

Police say the bombs were each made with less than 10 pounds of high explosives, which made them easy to conceal.

Globe correspondent Sarah Liebowitz contributed to this report from Leeds.