I am surprised there are not calls from America’s parents that their children NEED TO BE ABLE TO FLEE from the classroom at any time.
You already know that they don’t care about your children’s learning. At least give them a chance to live. This is like watching the PLO in the 70’s running the airlines.
Interestingly, in Japan, each classroom has a long aluminum pole with a semi-circle attached to the end to trap an intruder.
Each classroom has opposite doors (inside doors and outside doors), and a panic button on the wall.
And, at least in elementary, each kid has a panic fob (fob with a string like thingy, that when separated, sounds a very loud and ear piercing sound), that is detached and activated
very easily...
(and very annoying)
(After lots of searching because I don't know what the pole is called, I found a tiny picture of one):

On the other hand, there isn't a gun issue in Japan, and the pole would have been no use back here in the states against a gun.
BUT, a gun in the teacher's desk would certainly help...