Police disclosed the names Monday of two of the suspects in last week's abortive bombings here and made a new plea to the public to assist the massive manhunt to catch the fugitives before they strike again.

Investigators raided an apartment in north London that neighbors said had been occupied by one of the suspects, named by police as Muktar Said Ibrahim, 27, also known as Muktar Mohammed Said. Police named the other suspect as Yasin Hassan Omar, 24.

Detectives said they had arrested two more suspects in north London under anti-terrorism laws, bringing to five the number in custody.

Meanwhile, an inquest into the mistaken killing of a Brazilian electrician by anti-terror police last week in a subway car revealed that the man was shot seven times in the head, not five as previously reported, and once in the shoulder. The head was targeted in an apparent attempt to prevent him from detonating explosives the officers wrongly feared were hidden on his body.

Prime Minister Tony Blair added his apology Monday to those of other officials while defending the shoot-to-kill policy that led to the slaying.

Police identified Ibrahim as the man suspected of setting off a detonator in a gray backpack containing explosives at midday Thursday on a double-decker bus in east London. The bomb failed to explode and Ibrahim fled the scene, according to the police account.

Three other men attempted to set off bombs in three subway trains about the same time in attacks that echoed the bombings on London's public transit system two weeks earlier that killed 56 people, including the four assailants. Investigators believe that the two attacks are linked and that leaders of the two cells of bombers might have met in northern Wales in early June to coordinate their plans.

Detectives have questioned Ibrahim's father and several family members, who were unable to tell them the suspect's whereabouts but provided a document with a photo of the man that the authorities released Monday, according to a confidential police source.

Family members, who live in a public housing complex in north London, refused to answer a reporter's questions Monday evening. Neighbors said that the family was of Somali ethnic origin and had lived in the complex as long as a decade, but that the son no longer lived there.

Police officials privately expressed frustration that they had not been able to find the four fugitives and that they had gathered enough information only to issue a reliable identification of two of them. "Someone somewhere knows these guys," said a police official, who spoke on condition of anonymity. "They really need to come forward now."

According to the official account released Monday, three of the suspects entered the Stockwell subway station in south London just before 12:25 p.m. Thursday, then set off for their targets.

The first man, who has not been named, attempted to set off a backpack of explosives on a Northern Line train heading toward the Oval station. When it failed to explode, he got out at the station and ran, chased by "extraordinarily brave members of the public who tried to detain him," according to police. But the man escaped into the nearby Brixton area, where he jettisoned a sweat shirt bearing the words "New York."

The second man, allegedly Ibrahim, entered the No. 26 bus at 12:53 p.m. and got off 12 minutes later after seeking to set off his device. The third, alleged to be Omar, tried to detonate his device aboard a Victoria Line train heading north, while the fourth, who apparently took a separate route to his target, sought to detonate a bomb on the Hammersmith and City Line near the Shepherd's Bush station.

The fourth man shimmied down from the raised train platform and fled through back yards, vaulting over fences and jumping 20 feet into a back garden, according to an account in the London Times. The newspaper said he burst into an elderly couple's home through the back door, raced through the house and ran out the front -- shutting the door behind him.

Police said all four would-be bombers carried backpacks holding explosives packed inside 6.25-liter (about 1.7-gallon) plastic food storage containers manufactured in India and sold at 100 outlets in the London area. An identical fifth device was found in a backpack in a wooded area in northwest London, not far from the site where the fourth bomber fled. Police appealed to shopkeepers and workers to come forward if they could recall selling at least five of the white-lidded containers to one person.

They said they could not explain the existence of the fifth bomb, but cautioned reporters against theorizing that it showed a fifth person was involved in the attacks.

Peter Clarke, head of the anti-terrorist branch of the Metropolitan Police, urged anyone with information on the four bombing suspects' whereabouts to call immediately for emergency assistance. "The public should not approach them," he warned in a briefing with reporters.

About 1 a.m., armed officers swarmed a block of high-rise apartments in the Barnet area of north London. They ordered residents on three floors to evacuate their homes, then burst into an apartment on the ninth floor.

Neighbors later told reporters that Ibrahim and two other men had lived in the apartment but that Ibrahim and one of the others had disappeared two to three weeks ago. One neighbor, who did not give her name, said she had run into Ibrahim and one of his roommates in the building elevator about a month ago while they were hauling as many as 50 small cardboard boxes up to the apartment. They told her the boxes contained wallpaper stripper.

Police have not identified the explosives used in Thursday's abortive attacks, but officials have said they were the same homemade materials used in the July 7 bombings.

Police are also pursuing a lead that the July 7 and July 21 groups may have linked up on a June whitewater rafting trip in Wales that two of the July 7 bombers are known to have attended. On Monday, the Associated Press quoted the head of the rafting company as saying that Ibrahim and Omar were not registered on the trip taken by the July 7 figures, Shehzad Tanweer and Mohammed Sidique Khan.

At a coroner's inquest in south London, a police inspector revealed that plainclothes officers had shot Brazilian citizen Jean Charles de Menezes, 27, seven times in the head and once in the shoulder at close range Friday morning after mistaking him for a suicide bomber. Horrified passengers in the subway car, where three officers piled onto Menezes while one shot him repeatedly, had said earlier that they thought he had been shot five times.

The shooter apparently was following a policy laid down by former police commissioner John Stevens, who wrote in the News of the World over the weekend that he had changed the standing instructions to fire at a suspect's chest after sending police teams to Israel, "where we learned a terrible truth."

"There is only one sure way to stop a suicide bomber determined to fulfill his mission: destroy his brain instantly, utterly," Stevens wrote. "Which means shooting him with devastating power in the head, killing him immediately."

The undercover agents had trailed Menezes from an apartment building they had kept under surveillance on suspicion that a terrorist might have lived there. They followed him to Stockwell, the same station from which three of the suspected bombers departed for Thursday's abortive attacks.

Police officials say they are still trying to determine why Menezes fled after police reportedly identified themselves at the station. One unsubstantiated claim that newspapers here attributed to unnamed officials was that he was living in London on an expired student visa and may have feared being detained. But family members said his visa was valid and current.

Blair, speaking after talks with French Prime Minister Dominique de Villepin, told reporters: "We are all desperately sorry for the death of an innocent person. I understand entirely the feelings of the young man's family."

But Blair added, "We also have to understand the police are doing their job in very, very difficult circumstances and it is important that we give them every support."

Menezes's death has continued to prompt outrage in Brazil. Foreign Secretary Jack Straw told reporters at a news conference Monday with his Brazilian counterpart, Celso Amorim, that the commission investigating the death would deal "sympathetically and quickly" with claims for compensation.

Special correspondent Audrey Gillan contributed to this report.

Mourners gather in Paisley, Scotland, for the funeral of Helen Jones, who died in the July 7 bombings. Jones, 28, was riding on the subway's Piccadilly Line.London police identified two of the suspects in Thursday's abortive attacks as Yasin Hassan Omar, 24, in top photo, and Muktar Said Ibrahim, 27.