LONDON -- A massive bomb rocked downtown Oslo on Friday and a gunman opened fire on a youth camp run by a political party in twin attacks that killed at least 16 people.
The explosion in the Norwegian capital occurred near Prime Minister Jens Stoltenberg's office, shattering glass and littering the streets with documents and other debris. But Norwegian media said Stoltenberg and members of his Cabinet were safe.
"We could feel the building shake. It was a huge blast," said Torbjorn Pedersen, a reporter with the newspaper Aftenpost. He ran onto the rooftop of his building after the explosion and saw smoke billowing up from the site of the prime minister's office.
On an island outside of Oslo, a gunman dressed in a police uniform opened fire at a youth camp run by Norway's Labor Party. Police said they thought the two attacks were related. The gunman was arrested.
Reports still were sketchy, but police said nine or 10 people appeared to have died at the youth camp, which was run by Stoltenberg's Labor Party.
Mattias Carlsson, a reporter for the Swedish newspaper Aftonbladet, who took a boat around the island, said in a telephone interview that he could see more than a dozen bodies lying on shore or floating in the water, many of them young women.
"There are four people and they are lying together as if they are hugging," Carlsson said of one group of bodies.
Other news reports quoted a witness as saying he had seen between 20 and 25 dead.
Video footage from the streets of the capital showed terrified people fleeing the scene to safety, heading away from Oslo's normally bustling downtown.
Nearly all the windows of one multistory building appeared to have been blown out. Another building was on fire. A huge plume of smoke rose into the sky. Authorities said at least 15 people had been hurt in the blast, which they said was caused by a bomb. The twisted, charred wreckage of a car was visible close to the blast site.
Residents were stunned by the blast and the possibility that their placid city, which hosts the annual ceremony awarding the Nobel Peace Prize, had become the target of a large terrorist attack.
There was no immediate claim of responsibility for the blast, but Norway has been singled out as a target by al-Qaida.
Almost exactly a year ago, three foreign-born Norwegian residents suspected of being affiliated with al-Qaida were arrested on suspicion of plotting an attack.
Last week, Mullah Krekar, an Iraqi-born cleric who lives in Norway, was charged with terrorism after allegedly threatening politicians with death if Norwegian authorities deport him. Krekar is the founder of the militant Kurdish Islamist group Ansar Al Islam.
In 2003, an audiotape by Ayman al-Zawahri, who succeeded Osama bin Laden as leader of al-Qaida after his death in May, urged militants to attack the U.S., Britain, Australia and Norway.
Many Norwegians were puzzled at the inclusion of their country on the list; explanations centered on Norway's participation in the war in Afghanistan.
Six years ago, many Muslims around the world and at home were angered when a Norwegian newspaper published cartoons from Denmark that protesters said insulted the prophet Muhammad.
Oslo is also a contributor to the aerial campaign over Libya.
(Chu writes for the Los Angeles Times. Special correspondent Alexandra Sandels in the Times' Beirut bureau contributed to this report.)