Ann's spot on with her analysis of the folly of hiring "armed guards" in schools. Make concealed carry by law-abiding citizens legal on school grounds. Then, a prospective mass murderer will not have the certainty that he will face a completely helpless group of people in a confined space.
It is that very uncertainty that the bastards at the New York newspaper destroyed with their disclosure of the addresses of armed citizens. Look at the unintended consequences of that -- correctional officers are being intimidated by inmates "Hey, I know where you live..."
These idiots are trying to incite a civil war.