Shooting people is not the answer,though some may need to be shot...lol. Just get the toughest guy at the field to run them off or call the police. At our field we have the problem of members bringing their whole family out and putting up tents adjacent to the runway.One plane out of control and hitting someone could shut the field down.I feel that only the member and one spotter should be allowed near the runway.Everyone else can stay behind the fence and still watch the planes fly.
I live in south Florida and the problem gets worse because most of these people don't speak English or refuse to understand what you are trying to tell them.Many of the people that have flown at this field for decades are looking elsewhere to fly(private clubs) before someone gets hurt or in a fight that shouldn't happen.We even have a gigantic rule board posted and "these people" seem to ignore it.

It's sad that some idiot will cause the whole field to shut down because they think that they are above the rules.
Oh hell,now I'm ready to shoot someone!