NOTHING will stop crazy people from being crazy, and that is the point I attempted to make. What would “stop” a person hell-bent on perpetrating an atrocity such as this with a claw-hammer? A well armed and trained citizen.
The same (and only) thing that will stop the atrocity being committed with any other weapon, guns included.
An unarmed middle-aged (or average female) teacher will not withstand a dedicated and sustained hammer attack by a motivated 20 something male, any better than they will withstand gunfire if they are not trained and equipped to defend themselves. The police, just like in the recent shooting, will arrive after far too many lives have been destroyed.
My point is this: No proposal offered so far will allow those charged with protecting these young lives while they are outside their parents care to be successful in doing so.
The only solution that I can see to mass murders of any type, in any location, will be tightly controlled return-fire by someone who is actually on the scene at the time the attack is taking place.
Again, I posit that you CANNOT stop crazy people from being crazy.
No. But the nut is not going to be able to catch and kill 20 kids running in all directions. It generally takes some time to reliably kill someone with a hammer (not that I have all the much experience at it), and meanwhile your intended victims are scattering in all directions.