The common denominator in all of those incidents is "schools". Therefore, if we got rid of "schools" there would be no need for Gun Free School Zones which seem to almost magnetically attract people intent on killing a whole lot of other people, and thus no more rapid mass murders at "schools"
Now, if you look at all murders committed since Cain killed his brother you will see that every single one of those murders was addicted to Oxydihydride during their lifetime. Eliminate Oxydihydride, and thus addiction to it, and who knows how many murders will not be committed.
On the other hand, uncountable orders of magnitude more people pass through Gun Free School Zones without bringing a gun to the school for the purpose of killing a bunch of other people. And the same holds true for even life-long addicts to Oxydihydride who never murdered anybody, or even think about murdering anybody.
It's science! http://tinyurl.com/abp9u7f