Should we ban gasoline, too? Back in 1988 Laurie Dann set off a firebomb in a school (thankfully it was not well-constructed and school officials were able to put it out). Then she tried to enter a daycare to set another firebomb, but the staff there prevented her from entering the building. That's when she finally entered a different school and shot and killed/injured kids. In less than a week of this occurring, my k-8 school instituted locked exterior doors and a buzz-in process for all visitors.
My hope is that maybe schools will start employing armed police or other specially-trained security to help would-be murderers that they will encounter armed resistance.