You folks have offered a great deal of wisdom above. IMHO, you're right - a search for the magic cure is useless. This is a problem with many origins. At this point, with a string of such shootings, it shows us the power of influence. Every nutcase kid in the nation now has a chance to see and think about these actions as an alternative. And, I'll bet the cynical, anti-self defense types are just loving this political help. Keep watching them as they shamelessly prey on these victims to continue pushing their political agenda.
In addition to the factors cited above, I would add the pervasive violence in our movies, TV and video games. Please hear me out. Take some time someday and read the psychological research into this subject - this stuff does desensitize people to violence. Does it cause most of us, or even many of us to go postal? No, of course not.
But I believe it's like a poisonous recipe. Mix a lonely kid, no religion or a 'black' religion of Satanism or other hatred, give him / her abusive parents, let 'em fail in school and be isolated by their peers, make sure they watch lots of violence on TV, movies and video games, humuliate them, and make sure you add no hope or positive role models in their sphere of life. Now, give them the smarts to find dad's / mom's / neighbor's guns and ammo. Guns and ammo that may have been there for 30 or 40 years, without harming a soul. And when those long guns, pistols and ammo see the light of day in this kid's hands, it is a new world. Now, a deadly world.
Why? Because the guns were there? I don't see how any logical human being could come to that conclusion. The only way anyone with gray matter could arrive at that conclusion is when they totally ignore the benefit in this deadly cost / benefit analysis - the comparison of the criminal use of firearms, versus the overwhelming defensive and other appropriate uses of firearms.
So, it comes down to cost / benefit, like so many of life's choices. And the kids who do such terrible things with guns? Well, it is so much easier to find a single convenient, politically-incorrect product like the gun. So much easier than actually taking a hard look at some of the more disgusting parts of our society, and pondering what we can really do to change those. Especially since many of them are such linchpins of liberalism.