Scott C.
Just one guy
What Explains U.S. Mass Shootings? International Comparisons Suggest an Answer
International studies pretty conclusively demonstrate that the sheer availability of guns is the decisive difference between the US and other nations in which mass shootings are significantly less frequent. Reduce the number of guns, reduce the number of mass shootings. It's that's obvious.
The availibility of guns might make it easier to pull off mass murder, but why do more people want to kill today than wanted to kill yesterday? That's a sign of something more disturbing than the existence of guns.