I bet the kids hiding under their desks would have loved to have a choice.
When concealed carry was first instituted in Florida, overall crime went down, but people in rent a cars leaving airports were targeted, (people do not have guns coming off planes.) Florida then passed a law that rentacars could have no distinguishing stickers...etc that identified them as rentacars, which stopped the carnage.
"Concealed" is the trick more than how many people actually carry.
I had a talk with a bunch of college kids after this incident. That is the time to go absolute ape sh!% emasse without regard to individual survival. That is hero time - not hiding under the desk and getting in line to be shot time.