A Norwegian gunman disguised as police officer killed at least 91 people in a ferocious attack on a youth summer camp of Norway's ruling Labour party, hours after a massive bomb blast that ripped apart a building in Oslo killing seven people and injuring more than 90.

Norwegian police confirmed Saturday morning that they had arrested Anders Behring Breivik, a suspect identified as right wing Christian fundamentalist who is responsible for both the bombing and the youth camp shooting rampage in Oslo, Norway Friday.

A massive bomb blast ripped apart a building, which was very close to the Prime Minister's office, in Norway's capital Oslo at 3.26 PM local time on Friday.

The news of the Oslo bombing reached throughout Norway via the radio. Around 700 youths had gathered on the Utoya island, owned by Norway's Labor Party, 30 km (20 miles) northwest of Oslo for a political camp. After hearing the bombing news, all 700 teenagers and young adults gathered together to discuss the incident.

The assailant came to the gathered youths posing as a policeman and told them he was there to review security. The teenagers thought a security drill was going to take place. Suddenly the attacker took out a machine gun and started indiscriminate firing, after screaming aloud that he was there to kill everyone.

CNN quoted Norwegian Labor Party member Bjorn Jarle Roberg-Larsen as saying that the attacker had accosted the group of youth posing as a policeman conducting a security check. After just a few minutes, he took a handgun and started to shoot people, Roberg-Larsen said.

Within an hour or so, more than 80 people, mostly teenage children, had been killed in the holiday island which will now be remembered as the grimmest graveyard in the world.

Reuters quoted Prime Minister Jens Stoltenberg as saying that the Norwegian officials are working with foreign intelligence agencies to see if there was any international involvement in the bomb and shooting that together have killed 91 people.

We have running contact with other countries' intelligence services, Stoltenberg said after meeting with survivors at a hotel near the scene of the island gun attack that killed 84. Some of the investigation is under way. Some of it is obviously to.... investigate whether there are any international connections, he said.

Take a glimpse of the aftermath photos of the twin attacks in Oslo, Norway:

Must Read: Norway Oslo Twin Attacks Kill At Least 92, King and Premier Survive Bombing [WARNING: GRAPHIC PHOTOS OF DEATH AND INJURY]h