I suggest that if you consider the scenario in real life, and people do, its called responding to an active shooter - in a primary school, a campus, a church, a workplace, a shopping mall, even a military base (Ft Hood). Lots of folks are responding to active shooters, far more than they are to isolated campus shootings, which are relatively rare. There are lots of similarities across these attacks. Lots of folks are giving thought to how to respond to active shooters, on a personal (victim) level, as police / SWAT, and as EMS. I like this article written from the EMS perspective:
http://www.jems.com/article/major-incidents/arlington-county-va-task-force. Especially this quote:
"In a paradigm shift following Columbine, police departments moved to an aggressive response in which police immediately pursue, establish contact with and neutralize the shooter; the idea is that the sooner the shooter can be contained, captured or neutralized, the fewer the casualties."
The idea of victim response to an active shooter isn't often dealt with as directly: most often the advice of first responders is to take cover, establish distance and barriers between yourself and an active shooter, treat wounded and wait for assistance. In short, protect yourself and the lives of others. I think though that the idea of rapid containment, capture and neutralization would allow for people in the direct path of an active shooter to take action on their own, with some general caveats:
- don't head out of your room or area in search of the shooter: armed or unarmed, you are more of a danger to yourself, other targets of the shooter, and to first responders. If not in the same area as the shooter, distance (evacuation) and barriers are your best protection.
- if you find yourself in the same room as the shooter, you have a split second choice to make: rush the shooter, hopefully with others, or take cover, and evacuate as possible. It seems to me that distance from the shooter and from available exits or cover is critical here. If you have to approach from across a room or down a shopping mall corridor, your odds of subduing a shooter before he can fire on you are diminished. Also, I submit that the situation will probably overwhelm even the most prepared person: we just aren't keyed to respond to a sudden and immediate threat to our lives in the form of an active shooter. Only training and experience can somewhat overcome that, and AFAIK no one provides potential victim response training (defn: contain, capture and neutralize, before the arrival of first responders).
Some folks however may be more predisposed to thinking on their feet and mounting an immediate attack - vets who have seen action, aren't panicked or overwhelmed by the sound of gunfire, and might have the training to subdue a shooter. In general I recommend sitting next to them in class...