It's not violent video games or violent movies. It's not novels, magazines, music or the evening news, for that matter. Or competitive sports.
It's men with bad ideas with access to weapons. We should limit their access to weapons. A hammer can be a weapon, yes, but it's also a handy tool, so it's dumb to compare a gun to a hammer. And no one can commit a mass murder with a hammer. Except the guy from "Oldboy."
Culture is not the problem. Men are the problem. We can't get rid of men. We can limit the means they have to kill innocent people.