[grobdriver]

Make different sounds for different locations so that the armed teachers know where to go to kill the intruder.

Hard enough to convince most teachers to gather their students, draw their weapon and hunker down until the police arrive, never mind gather your students and then leave them alone to go hunt the hunter - and risk getting shot by the police when they do arrive.

If every teacher were to assume the armed defensive role the shooter will run into someone shooting back in short order.

[1Old Pro]

and risk getting shot by the police when they do arrive.

LOL, yea, that's not a risk.