Real gun-free zones (enforced by metal detectors backed up by armed security guards) are fine for certain buildings. Pretend gun-free zones (bans on gun carrying by licensed people, but no procedures to keep out criminal gun carriers, and exacerbated by the absence of armed security) are magnets for mass killers. There is a reason why mass killers frequently attack schools, movie theaters, or shopping malls which are pretend gun-free zones. My article Pretend “Gun-free” School Zones: A Deadly Legal Fiction, 42 Connecticut Law Review 515 (2009), examines the policy arguments. The article details some (but far from all) of the instances in which a lawfully-armed person at the scene has thwarted attempted mass murders. The reason that everyone knows about Sandy Hook Elementary, and few people know about Pearl High School is that the latter had a Vice-Principal with a gun.