Sorry, but as someone from Britain, there does seem to be a very obvious solution to stop people shooting each other, which is far more obviously effective than blaming the games which are designed for entertainment for it, or blaming the government for not having enough security, which is to get rid of those devices which are designed solely to kill and/or maim people as quickly and powerfully as possible, ie the guns! Whether or not it turns out that there would be less shootings than there currently are if computer games were all destroyed completely, I'm pretty sure that if no one had guns instead then there'd be less!
Now, as I say, I'm not from and have never been to America, but is missing this somewhat obvious idea through simple stupidity or some cultural ideal which somehow involves everyone having a gun so no-one dares shoot anyone: an idea which clearly isn't working (partly because it seems it's mainly the people who can't have guns for obvious reasons, and fortunately still don't, eg children, who are targeted.)