Think it through; you might get into something you can't get out of. Using weapons to commit a crime will get you some serious time, and it doesn't matter what reason you give the cops. Oh, and getting a group of people to help you will only liken the chances you'll get caught. Somebody is gonna brag, and word will get back to the gang or the cops and they'll be after you.
Me knee-jerk reation was to tell you to do something to them, but honestly you should just walk away from it. If you resort to violence you're no better than they are.
I've had stupid crap done to my cars, so I know what it's like. I once had some kids pour used motor oil all over both our cars, and they scratched the paint on my neighbor's car. I fixed them though; they were hitting all the neighbors, so I got them on videotape the next night and then let the cops see it. They handled it for me, and I never had any trouble from them after that.
I've also had my radio jacked 3 times, hubcaps jacked, and my house robbed 3 times as well. All I can tell you is to insure your stuff.