I recently took part in active-shooter training as part of my job. One of the suggestions was to keep one or more canned good items in my desk to use against a possible intruder. The message was that someone who comes into a building wanting to kill has the goal of killing as many people as possible in as short an amount of time as possible because he knows it’s likely he’s not going to come out of it alive.

So, if there is resistance of some sort, even in the form of canned goods flying at him, the shooter may very well move on to what he hopes will be an easier target. If the next target is also throwing cans, who knows? Maybe the would-be shooter will keep on moving until he moves himself right into a nice spray of bullets.