The problem is not an ideological one, the problem is the mental status of these people, better said they are assholes who can and are motivated by what they see on the news or the movies or online, and their is a lot of hate out there, from all quarters. Contrary to what the NRA says guns do kill, if you don't have a gun available you probably won't kill, I am not against someone having a gun, if he can prove he is capable of using it and takes a mental test. The thing I find ridiculous is the availability of semi automatic weapons in the US, what the hell does a person need one of these for? Hunting? Do you think you need a semi automatic rifle to kill a deer?
But these school shootings are apparently an issue only in the US,
I don't know why. You are lucky in Germany, I am from Honduras, we have a ready supply of all types of weapons, an incredible amount of AK47's and the murder numbers show it, but murders here are hits, robberies, vengeance or maybe drunken fights, no school shootings, could there be dark organizations that psychologically brainwash the kids who do this, you know to keep the population frightened?