Here's an example of a person "talking down" a bad guy with a gun using words rather than weapons. Teachers would probably benefit more from classes in crises intervention rather than a trip to the shooting range. Here is another example of the need for universal background checks and a better mental health treatment system.
http://www.alternet.org/civil-liberties/unarmed-woman-prevents-school-shooting-words-not-bullets
http://www.alternet.org/civil-liberties/unarmed-woman-prevents-school-shooting-words-not-bullets