Again, how many of these teenage shooters are on Ritalin or other psychotropic drugs? I've read a few articles that claimed many or most of them were drugged.
Don't know if that's true or not, but if true maybe the use of those drugs should be looked into. Waiting for some article revealing the actual numbers of these shooters drugged up.
Incidentally, although it's easier said than done, and failing being armed himself, the teacher did the right thing as far the correct method to stop a shooter. He took three bullets, and anyone charging a shooter like that will probably get shot.
But students/people attacking the shooter will save more lives than cowering in a corner of a room like the students at Virginia Tech. Charging the shooter, throwing objects at him, or using desks for shields and charging will work a lot better than waiting for a bullet or hoping the shooter runs out of ammo.