While I offer no solution, I am reluctant about arming teachers and offer this...
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claim that “gun-free zones” invite mass shootings has been thoroughly debunked by research showing that the overwhelming majority—nearly 90%—of all high-fatality gun massacres since 1966 have occurred wholly or partly in locations where civilian guns were allowed or there was armed security or law enforcement present.11
Guns in Schools | Giffords Law Center to Prevent Gun Violence