After the Dunblane massacre in Scotland, here in UK all schools now have a security system in place where one has to identify oneself via an intercom before the door is unlocked for admittance. I retired before this became the norm. It's a terrible climate in which to educate youngsters. I feel it was intense and uncontrollable anger which drove this young man to commit these atrocities. Many posters have said we need to identify and help such people before the anger beomes dangerous. Not so easy.