Whenever something like this happens I always see news spots about gun control, the parent are to blame, the kid was ****ed, etc etc.. Never "does our culture somehow breed this behaviour?" "Why do we have so many shootings, could we as a society be doing something wrong".. It's, from my point of view, always focused on the regional or laws. Maybe it's just easier to dismiss when it's such a huge country, but I would never blame gun control or lack thereof, if people started going crazy here - I would naturally assume that something in our culture was leading instable kids to the conclusion that murder was the only way out. Espeically if was this frequent.
As for better sources on school shootings.. To be fair we would need to compare all kinds of violence in schools, from knife attacks and shootings to regular beatings - and then see if America has a higher frequency. I'll have better time wednesday, so I'll try to see if I can find some articles about it.
I've seen reports asking what you said - although that just leads to more magic bullet type solutions such as games, violent movies, lack of family values or what have you. Focusing on the regional law makes sense for the US, as things vary so much from state to state or so I think. Hard to know what Americans are doing as whole, heh, but I doubt they're thinking but ignoring some problem with their "system" or way of life or whatever. They have others lined up to tell them, anyway