How To Stop School Shootings
No, the answer isn't "More gun control!" Which is another way of saying, "Dooo something!"
Gun control is no more effective at stopping people from getting guns than the drug laws are at stopping people from getting drugs. I can get either just blocks from my house. All it takes is the cash.
You stop school shootings by having two or three people on campus who have more than their bodies to try to stop the shooter. Ideally, the principal of every school and one or two other people should have guns, safely stored or worn, and there should be measures to make sure there is a backup person (or persons) in case of their departure from the school (like at lunchtime) or illness.