There is a simple lesson here. Unarmed security officers can't protect themselves let alone others from armed killers.I spent a very brief time as a security guard at the Texas Department of Child Welfare Services in San Antonio. There were usually 3 or 4 guards on duty, as well as one armed police officer. As you can imagine, a place that looks out for child welfare often involves protecting that child from his/her biological parents. I saw a lot of scumbags coming through that door. But get this: the guards were at the front entrance, supervising the entry of every single person (employees and "clients") into that building. The armed officer was about 100 feet down the main hallway, closer to the center of the ground floor. Due to the "security" design of the entrance, there was basically no way to escape if a violent person had come in through that front door. On the other hand, the officer on duty would have been easily able to hear the gunshots that would be dispatching us and be able to react in some way. It wouldn't have done us, or the receptionists, one bit of good. We would all be deadmeat.
Fortunately during my time there, we had no such people come through the door. I couldn't even get away with carrying concealed, because the security guards had to be scanned in as well. I couldn't even keep my Swiss Army Knife on me while on the job. My personal defensive weapon was safely (and distantly) stowed in my vehicle, which may have given me a chance if I happened to be the one patrolling the parking lot when something went down. I fully understand where this commentor is coming from.