Just thought I'd pass this bit of useful info along.

If people are making mischief outside, parking lot, whathaveyou...calling the police is good, but it usually takes about 45 minutes for them to show.

I find that a camcorder pointed in their general direction makes whatever is going on stop immediately. It doesn't even have to be turned on. Camera lenses make people incredibly shy, and they don't really want their lives turned into a reality show.