The fact is that laws won't prevent this. When I was in the fourth grade, I took my new Model 94 Winchester to school for Show and Tell. It was pretty common. And, this happened in the Seattle Public School system. So essentially, I walked 3/4 of a mile back and forth to school with a hunting rifle, and no one said anything.
In 1981, MTV totally began destroying the attention span of our youth. The first time I saw it was in Miami at a friend I knew in Vietnam's house. We looked at that and said "This, along with drugs, is really going to mess people up". Images since then have changed so fast that nothing means anything any more. That is, except for slow motion, high definition gore. What do you think they should have expected from that?
So, much in the way that laws have prevented heroin addiction, they will have the same effect on the mass shooting problem. Just make a law that all the criminals have to surrender their weapons. That should fix it. /sarcasm