Gun free zones are a great idea. Someone planning a mass killing knows that there will be no guns around so they have no worries of being shot at.
Once you have decided to kill one or a number of people I really doubt that adding a few extra years on to a life sentence or death by lethal injection would tend to enter into the persons thought process.
The only thing that a gun free zone does is make some people feel better. While making a better target for those that have nefarious plans because it will be a longer reaction time.
An interesting thing...................after the Marjorie Stoneman Douglas school shooting, a Republican said we need to end gun free zones.
GOP state rep calls for end to gun-free zones after Florida shooting
But, in this article about the Marjorie Stoneman Douglas school shooting, there was an ARMED SCHOOL RESOURCE OFFICER, who failed to do their job and stayed outside instead of going in and confronting the gunman.
Florida school shooting: School resource deputy stayed outside - CNN
So, even in places that are designated as gun free zones, there can still be armed people authorized to be there with guns. And, like I said, if you are going to arm someone to protect the students, make sure they have the stones to do the job and not puss out like the school resource officer did.