So, what do we do? Build fortresses? Ban gun types? Assume that just because a school or community hires an armed guard, he or she is likely to cause more harm than good? A school shooting is the liability of all liabilities.
And in the case of Columbine, the guard didn't create a situation where panicked kids screamed and ran around. He and his back-up successfully evacuated students before SWAT even arrived.
There's something we can start working on immediately.
Meanwhile: more funding not for arming teachers but for counseling, psychologists, more teachers so there are smaller class sizes. Better resources to identify and connect with troubled kids exhibiting signs of anger and violence.
But yeah. Ban high capacity rapid fire weapons immediately. Make it so that only outlaws have them, so that the outlaws can be arrested and punished for owning them.
What will likely happen: Law abiding citizens will turn them in (let's hope for a buyback program). If they don't, and they hide them, great. Nobody ever has to know you have them.
These kids use these weapons because they're easy to obtain. Opportunity. They would do way less damage with a handgun or a bolt action rifle. These automatic and sem-automatic weapons are designed to kill as many humans as possible as fast as possible. Make it harder. Give people more time to get away. I mean that's like the least we can do?