Shooting Logic through the crazy

So I'm wondering if the sick psychopaths at the NRA who are calling for arming all teachers thought about this possibility....

Say a teacher, or even security guard or principal is not having a good day, which happens to every one of us. Say a student acts up, which happens every day, what is to stop that teacher, security guard, principal from shooting that student and every other student in that classroom or school?

Sorry NRA more guns ARE NOT THE ANSWSER