Those are both really good points, thanks.

While a school shooting is what got me thinking about this, I didn't mean to limit to that specifically; my pre-cached thought on mass murders is "if people in the crowd had been armed, the shooter would have been stopped quickly". I phrase it that way to emphasize that I have no real evidence there.

Spending time training people to help those around them, in general, as a possible solution, though ... I admit that I'd honestly never thought of that. It doesn't just apply to teachers, either; one can imagine corporate "sensitivity training" that included basic lessons in how to identify/help/console a coworker who seems to be having a rough time lately.

I'm not sure that we are culturally capable, even in theory, of identifying the actual impact of such a program, but it's a hell of an idea.