Asif Hanif grew up in a sleepy London suburb, did well at school, studied business and left home for university.

This week, Israeli officials say, the 21-year-old blew himself up outside a Tel Aviv bar, killing three other people.

Residents of his neighborhood struggled Thursday to connect the Pakistan-born Hanif -- an occasional worshipper at a mainstream, multicultural mosque -- with a militant willing to kill and die for the Palestinian cause.

"As I know him, he was honorable and very polite and I never heard about any kind of politics from him," said neighbor Mohammad Hashmi. "I can't believe it."

Israeli authorities say Hanif and 27-year-old Omar Khan Sharif from Derby in central England carried out Wednesday's bombing. Hanif died; police believe Sharif fled when his bomb failed to detonate.

The men's British passports were shown on Israeli television and reproduced in British newspapers Thursday.

British officials said they were investigating whether the passports were genuine and couldn't yet confirm the men's identities. London police said anti-terrorist officers were assisting Israel in the search for Sharif.

Wednesday's attack -- claimed jointly by Hamas and the Al Aqsa Martyrs' Brigades -- was the first homicide bombing by a non-Palestinian in 31 months of fighting.

Israeli authorities believe Hanif and Sharif set out from the fenced-in Gaza Strip rather than the West Bank, which has a porous frontier with Israel and has been the starting point for most homicide attacks. As Britons, they could circumvent the tight security that keeps most Gazans from entering Israel.

There was no Israeli police comment on how Hanif made it to the Gaza Strip in the first place. But because he had a British passport, it would not have been difficult for him to enter Israel at the airport and enter and leave Gaza through Israeli checkpoints.

Hanif would be an atypical homicide bomber. He moved to Britain as a child and grew up in Hounslow. His family lives in a crescent of modest red brick homes, quiet save for the roar of jets from nearby Heathrow Airport.

Residents of the ethnically mixed neighborhood say it is a friendly street, with the usual problems of occasional burglary and rowdy teenagers.

There was no sign of trouble from Hanif.

Kevin Prunty, head teacher of the school Hanif attended from 1992 to 2000, said he had been "a well-liked, a respected pupil" who completed a course in business studies.

After school, Hanif enrolled at the University of Damascus in Syria, Prunty said. Hanif's brother was quoted as saying he was studying Arabic and intended to return to teach children in England.

His brother, Taz, told The Sun Asif was not the kind of person to carry out a homicide bombing.

"He was just a big teddy bear," he said.

Taz Hanif told the newspaper he and his brother had last spoken two weeks ago, when Hanif said he was fine and still at university.

On Thursday night British Broadcasting Corp. television quoted Sheik Omar Bakri Mohammed, leader of the small Islamic group al-Muhajiroun in London, as saying that Sharif and Hanif had both come to him for instruction.

"I knew both of them...as students," the sheik told the BBC, which described his group as Muslim fundamentalist.

The son of a successful businessman, Sharif is married with two daughters. Neighbors said they saw him near his home in Derby days before the attack.

Several Britons have been convicted of involvement in Islamist terrorism, including Richard Reid -- sentenced to life in prison in the United States for trying to blow up a trans-Atlantic airliner with explosives hidden in his shoes -- and Ahmed Omar Saeed Sheikh, convicted in Pakistan for the murder of American journalist Daniel Pearl.

British anti-terrorist investigations have focused on the Finsbury Park Mosque in north London and its fiery cleric, Abu Hamza al-Masri, who is fighting a deportation order.

Inayat Bunglawala, spokesman for the Muslim Council of Britain, said Hanif had been seen distributing pro-Palestinian leaflets outside a mosque in Hounslow.

But neighbor Hashmi, a former imam at the Hounslow Jamia Mosque, said he had never heard the young man speak about Palestine. He said Hanif had not stood out as a leader at the mosque.

The mosque's chair, Suleman Chachia, said Hanif had attended prayers for at least the last two years. "He didn't seem aggressive at all," Chachia said.

"We are not only shocked, we are a bit apprehensive when people hear about our mosque in connection with this," Chachia said, adding that homicide bombing was "un-Islamic and we condemn it completely."