LONDON — British police arrested a fifth suspect Sunday in their frantic nationwide manhunt for the perpetrators of failed bomb attacks in central London and at the Glasgow international airport.
Authorities also carefully searched a suspicious vehicle outside the Scottish hospital where they had taken one of the Glasgow suspects, who suffered severe burns when he drove a Jeep Cherokee into the glass entrance to the main airport terminal Saturday. Security officers also temporarily shut down a portion of Heathrow Airport on Sunday to investigate reports of a suspicious package.
The new arrest came in Liverpool, where a 26-year-old man living in a low-income district was detained and taken to the high-security Paddington Green police station in London. Liverpool police said the arrest was made in connection with the two car bombs discovered Friday in central London.
TV reports said one key suspect remained at large but did not identify him.
New clues were surfacing almost hourly, and links between the London and Glasgow incidents were "becoming clearer," said counter-terrorism chief Peter Clarke, briefing reporters in the Scottish city.
Prime Minister Gordon Brown, himself a Scotsman, on Sunday urged British residents to continue to remain calm, even as the nation's terrorism alert rating remained at "critical," the highest level. In the first TV interview of his premiership he told the BBC One "Sunday AM" program that he recognized the present terrorism threat as "long term and sustained."
"[But] it's very important," he added, "that we the British people send a message to terrorists that they will not be allowed to undermine our British way of life."
On Sunday night, tens of thousands of people, undeterred by the threat of additional attacks, attended a London concert organized by Princes William and Harry as a tribute to their late mother, Princess Diana, on the day she would have turned 46. The concert, which featured performances by artists such as Duran Duran and Elton John, was guarded by armed police officers.
Armed officers, normally a rarity in Britain, patrolled public places across London on Sunday and are expected to remain on the streets indefinitely.
In his first public comments on the attempted bomb attacks in Britain, President Bush on Sunday praised the "very strong response" by Brown's government.
"It just goes to show the war against these extremists goes on," Bush said. "You never know where they may try to strike."
Security was stepped up at British airports and train stations, and spot checks on cars had begun around the country. In the U.S., Homeland Security Secretary Michael Chertoff said that increased security measures would take effect.
"We do not have at this point specific credible intelligence that there is ... a particular attack focused in this country," he said on "Fox News Sunday." "We do, however, view the summer as a period of special vulnerability."
In Glasgow, police continued to hold the two men who drove the Jeep loaded with explosives that burst into flames as it hit the doorway to Terminal One of Glasgow Airport. The driver was in critical condition and under guard in the nearby Royal Alexandra Hospital, suffering burns over most of his body. The passenger is in police custody in Glasgow.
The police found no explosives in the suspicious vehicle outside the hospital. The vehicle was blown up in a controlled explosion.
Police in white forensic suits searched properties Sunday morning in the small town of Houston near Glasgow, among them reportedly the home of the arrested men.
According to the first minister of Scotland, Alex Salmond, there were indications "that these people had not been in Scotland for any length of time." Evening TV reports said all the suspects were of Middle Eastern nationalities. Neighbors interviewed by the BBC described them as quiet people who had lived in the neighborhood for a few weeks.
The two people arrested on the M6 highway in northern England early Sunday were described as a man and a woman in their mid-20s.
Liverpool police made the arrest Sunday after closing down the city's John Lennon Airport on Saturday night, where they investigated a suspicious car.
By Sunday afternoon both Glasgow and Liverpool airports were reopened under tight security with cars prevented from approaching Glasgow Airport. Similar security measures are in force in most other airports nationwide.
At Glasgow Airport, the burned-out shell of the Jeep was finally removed from the shattered doorway of Terminal One on Sunday evening and taken for further forensic tests.
A report Sunday night said that burned canisters of liquid gas had been found inside the vehicle.
In central England, police were carrying out forensic searches of houses in Newcastle-under-Lyme, in the county of Staffordshire. Neighbors told British reporters that the man arrested on the M6 highway lived in one the houses searched and that he was a physician from Lebanon who worked at a local hospital.