The Associated Press has an article about an explosion in Oslo and shooting spree by a mass murderer posing as a policeman on the nearby island of Utoya. Some of the dead drowned while trying to escape from the gunman. One suspect, Anders Behring Breivik, 32, has been arrested.
UPDATE1: A Herald-Sun/AP article provides some additional details about Breivik's "right-wing" views. It turns out he had neo-Nazi and anti-Muslim tendencies (many conservatives do not recognize Nazi as right-wing), and was not being watched by the police as they had little documentation on him, and he had maintained a low profile until yesterday.
UPDATE2: According to a CNN article, the death toll for the Oslo-Utoya massacre has risen to 92. Police are looking into the possibility of more than one perpetrator, as witnesses on the island of Utoya said that another person in addition to Breivik was shooting people.