A man suspected of killing at least 92 people, most of them teenagers, in an explosion and shooting rampage in Norway surrendered to police as soon as they arrived on the island where he'd slaughtered most of his victims, police say.

By then, he'd been firing shots at young campers for 90 minutes, investigators said during a news conference Saturday. Police arrived on the island 40 minutes after being called, they said.

A 32-year-old man, who police say dressed up as a police officer before gunning down at least 85 campers at the youth retreat near Oslo, has admitted to some things already, such as firing weapons on the island, investigators said.

But it was unclear Saturday whether the suspect had confessed to launching the bomb attack in downtown Oslo, followed by a shooting massacre at an island retreat hosted by the country’s ruling party.

As victims' families gathered in a nearby hotel on Saturday, police continued to search the waters around the island of Utoya for campers who tried to save their lives by jumping into the water.

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Four people were still missing by early Saturday evening local time, and police said the toll from both attacks could rise.

Police said they will not identify the victims or reveal their ages until after they finish work on the island. They are also talking to all survivors.

A search of the man's home and his Facebook postings turned up suggestions of right-wing and anti-Muslim political leanings, said police, who didn't reveal anything that might have propelled the suspect to mass murder.

"It’s not clear what his motivation is yet and the police haven’t really talked about that," CBC reporter Nahlah Ayed said from the scene outside Oslo on Saturday. "What we do know from police is that he has been very co-operative and is very keen to express his point of view."

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A unidentified survivor from the shooting at an island youth retreat reacts as she embraces a man outside a hotel where survivors were being reunited with their families on Saturday in Sundvolden, Norway. (Matt Dunham/Associated Press)

The Norwegian-born suspect comes from a well-to-do family, and his Facebook page suggests he's a Christian fundamentalist. He owns a farm, where he runs a business, and once belonged to the right-wing Progress Party, according to reports. Police said the man doesn't have a criminal record.

Little else is known yet about the man's background, including whether he served in Norway's armed forces, although all men in the country are liable for military service after the age of 18.

Government officials reported killed

On Friday, the blast in Oslo came first — a car bomb set off outside a government building that housed the prime minister's office. Seven people died, including some government officials, according to Prime Minister Jens Stoltenberg.

During the chaos that followed the explosion, word came of the shootings on Utoya.

The two attacks formed the deadliest day of terror in Western Europe since the 2004 Madrid train bombings killed 191.

Norwegians were still reeling Saturday, and the streets of Oslo were only beginning to show life after looking like a ghost town in the hours after the attacks.

"It takes a special kind of cruelty to target kids and shoot them down, and it's absolutely horrible," Sigrid Kleiva-Gramstad told CBC News from Oslo as she explained the shock and grief in the country.

Norway's King Harald, Queen Sonja and Crown Prince Haakon went to Sundvollen to meet the families of victims of the youth camp massacre.

Stoltenberg also tried to comfort the families, whose children were at the annual retreat for political training and debate as well as for sports and more conventional camp activities.

Meanwhile on Saturday, Canada's Foreign Affairs Minister John Baird spoke with his Norwegian counterpart to offer his condolences and provide any assistance the country might need.

Car bomb an 'Oklahoma City-type' device

A Norwegian newspaper reported the suspect in the twin attacks bought about six tonnes of artificial fertilizer about 10 weeks ago, while a police official called the device an "Oklahoma City-type bomb" — in reference to the U.S. city's bombing disaster in 1995 that killed 168 people.

Artificial fertilizer can be used in homemade bombs, but the supplier in this case says the amount allegedly purchased by the suspect was normal for farm use.

Initially, police said they believed the assailant acted alone, but the CBC’s Ayed said they were more cautious on this point Saturday, since it wasn’t clear how one person could have pulled off both attacks.

"This was a very sophisticated attack, multi-pronged," she said.

A police official told reporters the suspect did not seem to have any connections to international organizations. The violence did not seem "Islamic-terror related," said the official, who would not allow his name to be used. "This seems like a madman's work."

The toll from the shootings at the youth retreat was initially estimated at 10, but survivors reported seeing many more victims. The number soared to 84 during the night, and an additional 3 deaths were reported later Saturday.

Killer’s police uniform fooled survivor

Survivors told harrowing tales  of the shootings. A 15-year-old camper named Elise said she heard the gunshots but felt safe after seeing a police officer. Then he started shooting people right before her eyes.

"I saw many dead people," said Elise, whose father, Vidar Myhre, didn't want her to disclose her last name. "He first shot people on the island. Afterward he started shooting people in the water."

Elise said she hid behind the same rock that the killer was standing on. "I could hear his breathing from the top of the rock," she said. She said it was impossible to say how many minutes passed while she was waiting for him to stop.

Other witnesses said the gunman also tried to kill people desperately trying to swim away from the island.

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Norwegian media have identified the suspect in custody as 32-year-old Anders Behring Breivik. (Reuters)

Though police did not release his name, Norwegian national broadcaster NRK identified him as Anders Behring Breivik and said police searched his Oslo apartment overnight. NRK and other Norwegian media posted pictures of the blond, blue-eyed Norwegian.

National police Chief Sveinung Sponheim told NRK that the suspected gunman's internet postings "suggest that he has some political traits directed toward the right, and anti-Muslim views, but whether that was a motivation for the actual act remains to be seen."

Stoltenberg, who leads the Labour Party but was not in his office when the explosion happened at government headquarters, told reporters he had spent many summers on the island of Utoya.

Island was 'paradise' for PM

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This Thursday July 21 photo shows young people on the Labour Youth League summer camp on Utoya island, Norway when Norwegian Foreign Minister Jonas Gahr Stoere made a visit. (Scanpix/Vegard Gratt/Associated Press)

Utoya is "my childhood paradise that yesterday was transformed into hell," he said at a news conference in the capital. He called the attacks a national tragedy.

"Never since the Second World War has our country been hit by a crime on this scale," he said.

The country was clearly in mourning, one Norwegian said.

"Norwegians consider Norway a quite peaceful and safe country," he said.

The island of Utoya is about 500 metres from one shore of Tyrifjorden lake, an oddly shaped body of water that is 25 kilometres at its longest and 12 kilometres at its widest. About 700 people were on the island at the time of the attack.

With files from The Associated Press