Now that's scary!!! Do you have outside lights that you can leave on all night? Flood lights would be ideal, but any light is better than nothing. Light the place up like a darn Christmas tree if you have to. Vandals don't like lights since they can't do much dirty work without been seen.
Please be careful, and don't risk a confrontation with them - just call for help if necessary. Sounds like a bunch of kids getting bored with their summer vacation and looking for some action. Here's hoping that they get caught and this will end quickly.