OSLO, Norway (AP) -- A bomb ripped open buildings in the heart of Norway's government Friday, and a man dressed as a police officer opened fire at an island youth camp connected to the ruling party. At least seven people were killed in the blast and nine more in the camp shootings, the peaceful nation's worst violence since World War II.
Oslo police said 9 or 10 people were killed at the camp on Utoya island, where the youth wing of the Labor Party was holding a summer camp for hundreds of youths. Acting Police Chief Sveinung Sponheim says a man was arrested in the shooting, and the suspect had been observed in Oslo before the explosion there.
Sponheim said police were still trying to get an overview of the camp shooting and could not say whether there was more than one shooter.
Aerial images broadcast by Norway's TV2 showed members of a SWAT team dressed in black arriving at the island in boats and running up the dock. Behind them, people stripped down to their underwear swam away from the island toward shore, some using flotation devices.
In Oslo, the capital and the city where the Nobel Peace Prize is awarded, the bombing left a square covered in twisted metal, shattered glass and documents expelled from surrounding buildings.
Most of the windows in the 20-floor high-rise where Prime Minister Jens Stoltenberg and his administration work were shattered. Other buildings damaged house government offices and the headquarters of some of Norway's leading newspapers.
Stoltenberg was working at home Friday and was unharmed, according to senior adviser Oivind Ostang.
Oslo University Hospital said 12 people were admitted for treatment following the Utoya shooting, and 11 people were taken there from the explosion in Oslo. The hospital asked people to donate blood.
The attacks formed the deadliest day of terror in Western Europe since the 2005 London bombings, which killed 52 people.
Sponheim wouldn't give any details about the shooting suspect, who he said was dressed in a police uniform when he opened fire into a crowd of youths.
A spokesman for Stoltenberg's Labor Party, Per Gunnar Dahl, said he couldn't confirm that there were fatalities at Utoya, about 60 miles (100 kilometers) northwest of Oslo. The party's youth wing organizes an annual summer camp on the island, and Stoltenberg had been scheduled to speak there Saturday.
"There are at least five people who have been seriously wounded and have been transported to a local hospital," Dahl said. He said the shooting "created a panic situation where people started to swim from the island" to escape.
Police blocked off roads leading to the lake around Utoya. An AP reporter was turned away by police about 5-6 kilometers from the lake, as eight ambulances with sirens blaring entered the area.
In Oslo, police said the explosion was caused by "one or more" bombs, but declined to speculate on who was behind the attack. They later sealed off the nearby offices of broadcaster TV 2 after discovering a suspicious package.
Ian Dutton, who was in a nearby hotel, said the building "shook as if it had been struck by lightning or an earthquake." He looked outside and saw "a wall of debris and smoke."
Dutton, who is from New York, said the scene reminded him of Sept. 11 -- people "just covered in rubble" walking through "a fog of debris."
"It wasn't any sort of a panic," he said, "It was really just people in disbelief and shock, especially in a such as safe and open country as Norway, you don't even think something like that is possible."
Public broadcaster NRK showed video of a blackened car lying on its side amid the debris. An AP reporter who was in the office of Norwegian news agency NTB said the building shook from the blast and all employees were evacuated. Down in the street, he saw one person with a bleeding leg being led away from the area.
The explosion occurred at 3:30 p.m. (1330 GMT), as Ole Tommy Pedersen stood at a bus stop 100 meters (yards) away.
"I saw three or four injured people being carried out of the building a few minutes later," Pedersen told AP.
At Utoya, Emilie Bersaas, identified by Sky News television as one of the youths on the island, said she ran inside a school building and hid under a bed when the shooting broke out.
"At one point the shooting was very, very close (to) the building, I think actually it actually hit the building one time, and the people in the next room screamed very loud," she said.
"I laid under the bed for two hours and then the police smashed a window and came in," Bersaas said. "It seems kind of unreal, especially in Norway. This is not something that could happen here, this is something you hear about happening in the U.S."
Another youth at the camp, Niclas Tokerud, stayed in touch with his sister through the attack through text messages.
"He sent me a text saying 'there's been gunshots. I am scared (expletive). But I am hiding and safe. I love you,"' said Nadia Tokerud, a 25-year-old graphic designer in Hokksund, Norway.
As he boarded a boat from the island after the danger had passed he sent one more text: "I'm safe."
The United States, European Union, NATO and the U.K., all quickly condemned the bombing, which Britain's Foreign Secretary William Hague called "horrific" and NATO Secretary-General Anders Fogh Rasmussen deemed a "heinous act."
"It's a reminder that the entire international community has a stake in preventing this kind of terror from occurring," President Barack Obama said.
Obama extended his condolences to Norway's people and offered U.S. assistance with the investigation. He said he remembered how warmly Norwegians treated him in Oslo when he accepted the Nobel Peace Prize in 2009.
The U.S. Embassy in Norway warned Americans to avoid downtown Oslo.
The attacks come as Norway grapples with a homegrown terror plot linked to al-Qaida. Two suspects are in jail awaiting charges.
Last week, a Norwegian prosecutor filed terror charges against an Iraqi-born cleric for threatening Norwegian politicians with death if he is deported from the Scandinavian country. The indictment centered on statements that Mullah Krekar -- the founder of the Kurdish Islamist group Ansar al-Islam -- made to various news media, including American network NBC.
Terrorism has also been a concern in neighboring Denmark since an uproar over cartoons of the Prophet Muhammad six years ago. Danish authorities say they have foiled several terror plots linked to the 2005 newspaper cartoons that triggered protests in Muslim countries. Last month, a Danish appeals court on Wednesday sentenced a Somali man to 10 years in prison for breaking into the home of the cartoonist.
Europe has been the target of numerous terror plots by Islamist militants. The deadliest was the 2004 Madrid train bombings, when shrapnel-filled bombs exploded, killing 191 people and wounding about 1,800. A year later, suicide bombers killed 52 rush-hour commuters in London aboard three subway trains and a bus. And in 2006, U.S. and British intelligence officials thwarted one of the largest plots yet -- a plan to explode nearly a dozen trans-Atlantic airliners.
In October, the U.S. State Department advised American citizens living or traveling in Europe to take more precautions following reports that terrorists may be plotting attacks on a European city. Some countries went on heightened alert after the May 2 killing of Osama bin Laden.
Associated Press reporters Louise Nordstrom in Stockholm, Matthew Lee and Rita Foley in Washington and Bjoern H. Amland in Hoenefoss, Norway, contributed to this report.
(Copyright 2011 by The Associated Press. All Rights Reserved.)