I think serious money needs to be spent on research and development of a more effective “No Guns Allowed” window/door/entrance sticker. /s
Shouldn’t a metal detector at each door work? With a video camera working in conjunction with it? With doors that are locked from the outside, to prevent anyone entering after school has started?
My granddaughter’s school in Texas, has locked doors, with a camera and a speaker, for those who have a legitimate reason to be allowed in.
Heck, my daughter’s Catholic High School had THAT, 35 years ago. And it was in a nice area, in a town with relatively low crime. (At the time).