Way back when in public HS (on another state) we had one armed guard (state police) and there was never an incident...and I can even say that he never had to pull his gun out to make a stop (even as fat as he was and with the thugs that we had).
Sheesh,
Back when I was in public HS, we carried Buck Folding hunters on our belts, shotguns or rifles in the trunk/back windows of pick ups for before & after school hunting and shooting trips.
We didn't need no armed guards.