As a retired risk management professional, I can assure you that proper risk management procedures and systems can go a long way in protecting children, teachers, and others in our schools.
Here are some examples:
1) Control all entrance doors. This may require armed security, metal detection devices and random checks of back packs and packages.
2) Isolate threats using sliding hallway gates, fog sprays, door locks, etc.
3) Maintain lock-down procedures that provide refuge areas not easily breached.
4) Maintain a monitored camera system that will make it possible to spot a weapon instantly.
5) Maintain a highly trained, but completely anonymous inside team of armed employees. No one knows who they are or where they are. Israel has had armed people in schools for decades.
Nothing can eliminate 100 percent of all incidents. But good risk management can limit losses. Pretending that gun control alone will do that is a serious mistake. We must start providing a higher level of protection in our schools.