I agree with the posts that qualify, train and arm teachers. They don’t have to pack, but the fact that no one knows whether they do or not is enough to deter mass murder. A single school resource officer could simply be the first target. In any neighborhood, a random burglar or meth addict has doubts about which houses are armed. This protects the whole neighborhood, even the anti-gun nuts. I see a lot of bumper stickers that say “This truck or this house is protected by Smith & Wesson”. I don’t see any houses that say “This home is a gun-free zone”. And yet, we say just that at our kids’ school. This is nuts!
My neighbor across the street a, 39 year military veteran, lets anyone know he is always within reach of a firearm. When he is working on his cars or truck in the driveway he has one on his workbench.