I don't know if you can do something about the sensationalism of the media. Even if you could, nowadays there's the new types of media which you can't really control.


(Emphasis on medical psychiatric researc):
It usually turns out that most of these guys were seemingly normal people. Maybe they were/are normal. Normal people can go batshit too.

Stricter gun control may help I think. But seeing that it's the US, this issue is pretty controversial. You know, the right to a set of beararms.
And you can't prevent it completely with that. Our gunlaws are much stricter but it happened here too (not as much, but still). Last year, some guy started shooting around with an AK and threw a couple of grenades in a public place. He got them from the black market.