LONDON -- With their investigation moving at breakneck speed, police sharply escalated their hunt yesterday for the plotters of attempted car bomb attacks in London and Glasgow that the British government called the work of terrorists linked to Al Qaeda. Officers raided homes in three cities and arrested another suspect, bringing the total to five, including at least one identified as a medical doctor.
Police said they had recovered an unusually rich trove of evidence from the vehicles and from video surveillance after two car bombs failed to explode in London on Friday and two assailants rammed a Jeep Cherokee into the entrance of Glasgow airport Saturday. The attacks prompted the British authorities to raise their terrorism threat assessment to its highest -- "critical," meaning a further attack is imminent.
One of the detainees was a medical doctor of Iranian-Kurdish descent, according to two people with knowledge of the police inquiry into the bombings. One of those people, and a BBC report, identified him as Mohammed Asha, 26, and The Sun newspaper said he worked at North Staffordshire hospital near the Midlands town of Newcastle-under-Lyme, where the police searched a house yesterday. The man was arrested along with a 27-year-old woman when the police pulled over a car in a dramatic operation on the M6 highway in northwest England late Saturday.
A second detainee may have been a hospital worker in Glasgow, a person with knowledge of the inquiry said. Yesterday the police carried out a controlled explosion on a car in the parking lot of a hospital near Glasgow where one of the bombers was in critical condition with severe burns after attacking Glasgow airport Saturday. Police said the car was linked to the bombers, but did not explain how.
None of the five suspects is a British national , a senior Western official said, raising a question as to who supported the group.
The disclosures also altered the thinking among security specialists about the nature of the apparently amateurish attack, raising questions about how exactly the bombers were tied to Al Qaeda. Despite British government assertions of a link, it presented no evidence.
British intelligence agencies had warned the government in April that terror attacks might be launched by Iranian Kurds to coincide with the handover of power from Tony Blair to Gordon Brown, who became prime minister Wednesday, according to a person who saw the warning. The government has not confirmed that report.
The people with knowledge of the inquiry requested anonymity because they were not authorized to talk to reporters. But Scottish officials said publicly that the two attackers who rammed the Jeep packed with gas canisters and gasoline into the entrance to the Glasgow airport were not from Scotland.
With the government's terrorism threat warning raised to its highest level, Brown said in a nationally televised interview: "We will not yield, we will not be intimidated, and we will not allow anyone to undermine our British way of life."
Britons already were edgy because of the looming anniversary of the July 7, 2005, London transit bombings, the country's worst terrorist attack, and Brown said the country was dealing with a "long-term threat. It is not going to go away in the next few weeks or months." He said Britain was "dealing, in general terms, with people who are associated with Al Qaeda."
The attempted attacks represent the first crisis for Brown. It remains unclear whether the location of the Glasgow car bombing was inspired by Brown's Scottish heritage.
Anxiety about events in Britain rippled across the Atlantic. "It just goes to show the war on these extremists goes on," President Bush said as he waited for President Vladimir Putin of Russia to arrive at his family vacation compound in Kennebunkport, Maine. "You never know where they might strike."
Authorities at Heathrow, one of Europe's busiest airports, briefly closed Terminal 3 while a suspicious package was investigated, which turned out to be harmless.
The investigation into the attacks seemed to unfold at breakneck pace because, security specialists and officials said, unlike most other terror attacks when evidence is destroyed by explosions, police have retrieved forensic evidence from vehicles and closed-circuit television and detained several suspects within hours of the bombings.
Police said yesterday that officers had searched homes at three locations -- at Houston, near Glasgow, in southern Liverpool, and in the Midlands location of Newcastle-under-Lyme in Staffordshire. The authorities have not identified any of the suspects.
Witnesses described the Glasgow bombers as being of south Asian descent. "The people we have in custody came to Scotland a short while ago to seek work," a senior police officer, John Neilson, told a meeting of Scottish Muslims in Glasgow's Central Mosque. "These are not your young people."
Scotland's justice secretary, Kenny MacAskill, said the two attackers who slammed the Jeep Cherokee into the check-in area entrance of the Glasgow airport Saturday were not "born and bred here. Any suggestion to be made that they are home-grown terrorists is not true."
Senior counterterrorism officers said the investigation was unfolding rapidly, but that it could take weeks to sift through a mass of evidence.
"We are learning a great deal about the people who were involved in the attacks," Peter Clarke, Britain's highest-ranking counterterrorism police officer, told a news conference in Glasgow.
He said the link between failed car bombings in London and the attack on the Glasgow airport Saturday "are becoming ever clearer" and he called the investigation "extremely fast-moving."
The Jeep used in Glasgow was also carrying propane gas containers but they did not explode when the vehicle, and its driver, burst into flames.
The car had not been stolen, the police said. The similarities between the styles of the attack have persuaded British investigators that they are linked, security officials in several countries said.
Security specialists said the police investigation had been facilitated by what a Western official called "an unprecedented amount of material to work with."