Prime Minister Tony Blair warned on Saturday of the "evil ideology" of Islamic extremists bent on inflicting terror as authorities on three continents widened their investigations into the London bombings.
Officials in the British capital raised the death toll to 55, and police in the northern city of Leeds searched an Islamic shop, the home of an Egyptian biochemist and another address for more evidence after investigators reportedly found traces of explosives in the man's bathtub.
Police on Saturday moved the twisted wreckage of the double-decker bus where one of the bombers and 13 other people died. The bus became a symbol of the capital's worst attack since World War II. Londoners and tourists stopped to watch as a flatbed truck with a police escort hauled it away to a secure location for more forensics tests.
Police also released an image captured by surveillance cameras showing all four bombers with backpacks entering the train station in Luton, north of London, on the morning of the July 7 attacks. Investigators say the four took a train from Luton to London's King's Cross station, where they split up to carry out the bombings.
Meanwhile, Jamaica's government has confirmed a man reported to have been one of the bombers was born on the Caribbean island but left as an infant. British authorities have identified the man as 19-year-old Germaine Lindsay.
The hunt for clues pointing to those who recruited, financed and supplied the four suicide bombers who blew up three underground trains and the bus focused on the men's ties to Pakistan. Authorities in Islamabad said Saturday they questioned students, teachers and administrators at one of two religious schools believed visited by one of the suspects.
Asad Farooq, a spokesman for the school, told The Associated Press that intelligence agents had been around on Saturday, but denied that the suspect, Shahzad Tanweer, had ever been at the school. British investigators say Tanweer, 22, carried out the bombing of the London Underground's Aldgate station.
Senior Pakistani intelligence officials said authorities were examining a possible connection between Tanweer and two al-Qaida-linked militant groups.
The U.S. television network ABC reported Saturday that the FBI was looking into possible ties between unidentified people in New Jersey and a Jamaican-born Briton, whom British authorities formally identified for the first time Saturday as Germaine Lindsay, 19.
The man has been linked to the worst of the suicide attacks a subway bomb that killed at least 26 people between the King's Cross and Russell Square stations.
FBI spokesman Ed Cogswell said Saturday the agency had no comment on any pending investigations.
Authorities raised the confirmed death toll from 54 to 55 after an injured victim died overnight at a hospital. About 700 people were injured in the morning rush-hour attacks, and police said more than 40 people remained hospitalized, at least six of them in critical condition.
In a speech in central London Saturday, Blair said authorities were facing an "evil ideology" in their struggle against Islamic terrorism.
"The greatest danger is that we fail to face up to the nature of the threat that we're dealing with," he said. "And what we are confronting here is an evil ideology. ... It is a battle of ideas, of hearts and of minds, both within Islam and outside it."
Investigators also continued searching a shop called Iqra Learning Centre in the Leeds neighborhood of Beeston. The shop appeared to sell Islamic books and DVDs and offer seminars and presentations.
Two investigators wearing white protective suits could be seen inside the store before officers covered the windows with gray plastic sheeting. The immediate area remained cordoned off.
The shop is about four miles from Egyptian biochemist Magdy Mahmoud Mustafa el-Nashar's townhouse, where British media reported that police found evidence of the explosive TATP inside a bathtub. Police continued searching the house on Saturday from behind large black and white sheets.
TATP was used by shoe bomber Richard Reid, whose attempt to blow up a trans-Atlantic flight from Paris to Miami in December 2001 was thwarted. Reid pleaded guilty to U.S. charges and is serving life in prison.
CBS News Correspondent Elizabeth Palmer reports the police investigation is evolving very fast, but that's little comfort to Britons who heard London's police chief tell them that another attack remains a strong possibility.
Muslim leaders have said the young bombers might have been inspired by radical literature. It was not immediately clear whether any of the four bombers had links to the shop, but neighbors speculated that the owner or manager may have met the suspects there.
Egypt's Interior Ministry said Egyptian authorities were interrogating el-Nashar, 33, who had studied for one semester at North Carolina State University and the University of Leeds. It said el-Nashar denied having any connection to the attacks.
Egypt is not prepared to hand el-Nashar over to Britain, Egyptian security officials said Saturday as British investigators arrived to sit in on the questioning. The two countries have no extradition treaty.
Britain's Labour Party, meanwhile, disclosed Saturday that bombing suspect Mohammed Sidique Khan, 30, visited the Houses of Parliament last year as the guest of Labour lawmaker Jon Trickett. It said Trickett alerted security officials when he realized Khan, who had worked as a counselor at a school in Leeds, was one of the bombers.
West Yorkshire police released a statement from Khan's family saying he must have been "brainwashed" and calling on people to "expose the terror networks which target and groom our sons to carry out such evils."
"We are devastated that our son may have been brainwashed into carrying out such an atrocity, since we know him as a kind and caring member of our family," the family said.
Samantha Lewthwaite, the wife of the Jamaican suspect, told The Sun tabloid newspaper she refused to believe he was among the bombers "until they have his DNA."
"He wasn't the sort of person who'd do this. I won't believe it until I see proof," she said. The newspaper said Lewthwaite was pregnant with the couple's second child and was under police protection.
In a statement issued Friday, the family of Hasid Hussain the 18-year-old believed to have blown up the bus said it was unaware of his activities.
"We would have done everything in our power to stop him," it said.