@tsarstepan,
Bring in the clowns!
I suggest they'll scare the malefactors.
There are eighteen slides of clowns on that link.
http://www.sfgate.com/world/slideshow/Clowns-gather-in-Guatemala-City-46548.php#photo-3239601
The kids of course would have met the individuals and watched them acting in clown suits, so no shocking of children.
Meantime, I'm following along, and I get farmerman's take, to date, whichever thread. I see his point but am chary.
I also remember going to Mexico in the sixties and Guatemala in the early seventies and seeing guys armored up sort of all over the place.
I'd rather find another solution.
I don't say every security guard is a clown, really, being a clown takes talent; or every clown is a natural security guard. Just that armed guards at every school is something my hundred year old aunt who taught in a school house on the san juan islands in the 19teens would frown at. She lived many years past that time and was a pithy speaker.