Why doesn't someone take pictures of the hooligans and send copies and a complaint to both mall management and the police? YOu don't have to confront them, report them - tell the mall owner/management they are losing customers as a result- if they feel the pinch in their profits, they will take steps.

If you file a complaint with the police, they have to take some action(even if it's just to investigate) or patrol - I know they probably won't catch the monsters but at least the complainant has tried.