Nah it was a joke, it's a 2 hour flight from where I'm at. I'm safe up here in the Narrow North.
My own theory, just to be controversial, is that it's right wing terrorists from Eastern Europe. Based on pretty much no information. By the way, apparently there was a polish video posted a few days ago that said something like "Explosion in Oslo 22.07.11" with the word "explosion" being in polish. Then like around when this happened today, the movie changed title to "hamsters". And then it's a video of some hamsters, with someone talking in the background, presumably polish. Damn you Simon.