Reply #2: It looks like this could be a home-grown extreme-right lone-wolf attack

[Apollo11]

According to BBC:

Norway has been hit by twin attacks - a massive bomb blast in the capital and a shooting attack on young people at a governing Labour Party youth camp.

At least seven people were killed in the bombing, which inflicted huge damage on government buildings in Oslo.

At least 10 more died at the camp, on an island outside Oslo, police say. One witness said he had seen 20 bodies.

Police arrested the suspected gunman at the camp and the government have confirmed that he is Norwegian.

Norwegian media reports said the shootings on the island, on the Tyrifjorden lake, were carried out by a man in police uniform.

Police later said that he was also linked with the bomb attack. Reports described him as tall and blond.

The prime minister and justice minister have declined to speculate on a motive behind the attack but police are saying that they believe the car bomb and the shooting are linked and that they have a suspect in custody from Utoeya.

The ministers are confirming he is Norwegian. During the day, after an initial focus on an al-Qaeda link, the possibility of domestic extremism increasingly came into focus.

The choice of targets - government buildings and a political youth rally - suggested a possible political agenda rather than the mass casualty approach typically employed by al-Qaeda.

http://www.bbc.co.uk/news/world-europe-14256712

On BBC TV in the UK, Newsnight (started 10 minutes ago) is going with the home-grown theory.

The Mayor of Oslo says it was probably a "crazy man". Journalists are speculating as to whether the perp may have had any real-world or online links with anarchist or neo-Nazi groups.