Shortly after a car bomb went off near the Prime Minister's office in Oslo, a (caucasian) dude disguised as a police officer showed up at the Labour party's political youth retreat on Utoya island and opened fire. With nowhere to go but the water, some folks were apparently shot trying to swim away. The killer is apparently in police custody.
Although some Islamic groups have claimed responsibility, it's believed to be an act of domestic rather than international terrorism. Norway has some small but hardcore right wing outfits, and the attack seems to be aimed squarely at the centre left/ social democrat ruling party.