Guns that are capable of mass murder have been prevalent in this country for well over a century. You could buy a gun C.O.D. from Sears Roebuck & Co, and many people did. Growing up in a small, rural town I remember that every pickup truck in town (including those in the high school parking lot) had a well stocked rifle rack, and most vehicles weren't even kept locked. We had plenty of fist fights but it never entered our mind to go get our gun.
So, what's changed ?, because it's not the availability, or access to, deadly firearms.
I'm not interested in debating "gun control " until someone can honestly answer that question. It's far easier for politicians and talking heads to attack guns than admit to, and deal with, the obvious social decay.
Until that honest debate occurs (if ever), it's time to give as much attentionand money to protecting children in school as we do to protecting movie stars, sports stars, politicians, airports, concert venues, etc.
Prayers to the families that have lost loved ones. My heart aches.