--- Secret service agent accidently fired one..... and he is extremely well trained in thier use... I am not rabid anti-gun (own-them) but having teachers with one will kill many more people by accident that it saves. Having one on campus (locked up) or in a car may make sense but not in any classroom or crowded hallway.
http://news.yahoo.com/oops-u-secret-almost-accidentally-shot-irans-president-072000986.html
http://www.theatlantic.com/magazine/archive/2013/04/deep-state/309260/ (better)