There are crazy people everywhere and there is no such country as a peaceful one. I guess we think of Scandinavian countries as such, because we don't know about them as much as we know about USA for example. Therefore, we would assume there is nothing wrong over there. Nevertheless, the depression and suicide rates are higher in northern countries, it seems it is due to the lack of sunlight.
Anyways, it is sad what happened, but I think what we need to do is not lament over the dead, but try to prevent such things from happening.