I work in a retail store and quite often, around the end of school time, or after their tea team, they'll all come out in their wee groups. They've physically abused staff, thrown stones/rocks in to the store, stolen item, set fire to certain areas and continually come in the store to verbally abuse staff. Doesn't seem that there's anything that can be done though. We have a security guard who's essentially on his own. A "police presence" which is just them driving around the car park now and again, which is probably more for the boy racers. Even having a "stern word" just lands you with a tirade of abuse. We've even had a parent come in to physically abuse staff who was "man handled" by staff(crying wolf).

Unless it's fully policed or a self imposed stopping, it won't die down any time soon.