This isn't really about gun laws imo, it's about America's relationship with guns and perhaps more importantly, why people actually go off their heads like this.
With or without gun laws they would still be going berserk - in the UK they just do it with knives (6 or 7 that I know of in London schools last week). For a serious comparison you would need to compare graphs on murders/violent attacks regardless of whether by gun, fist or other means.
I bet this is pretty standard in the US vs countries that have strict gun laws.
Its harder to kill 30 people with a knife
As opposed to allegedly so civilized moslem societies that produce suicide bombers at much higher frequency? At least our nutjobs have mental illnesses for an excuse rather than religion.*
* Not that some christian countries are not also so afflicted in the present and past.