They've got bulletproof whiteboards now...
https://www.hardwirellc.com/collecti...of-whiteboards
Just rip it off the wall and hide when the bullets start flying.
Ooooooor, start investing in mental health for all kids and especially troubled ones. When he was a student there, this guy was not allowed to carry a back pack on campus cause he was nuts. Maybe that's a good place to start.