No active shooter event has been foiled or stopped except by someone with a weapon in the last fifteen or so years. Go ahead, everyone dial 911. Let's see high school 1100 students and faculty that ought to just about swamp the 911 center's ability to handle any emergency. In all fairness to the folks that put the video together, it's based on the "gun free zone" concept. I.E. no law abiding person would ever bring a gun into a "gun free zone". And for the most part they are right. Course it doesn't stop the badguys from bringing one in and shooting up the place.