http://www.aftonbladet.se/nyheter/article13362762.abThere's photos of the explosion. Initial thought is that Energy & Oil Department was the target, but the explosion was in the government district. Norway is one of the largest and the most stable oil producers in the world. Probably relating to the trial against Mulla Kreka. Looking over the photos, I really doubt it was an accident. It was likely a car bomb. Good news, looking at the photos, it looks like the brick on the target building acted like ablative armor and kept the main concrete supports from being significantly damaged.
Majority of the injuries were from glass and other small objects caused by the overpressure. If they had installed security film over the windows, casualties would have been a lot lighter.
Also, there was a shooting, it took place on an island used owned by the Norwegian Social Democrats, the ruling party. Someone dressed up as a police officer and attacked a summer camp for a political youth organization. Ferries are cancelled from there now, people are trying to swim to the mainland.