Wrong answer.
You deal with these thugs the way thugs have been dealt with for thousands of years:
Meet force with force. Gangs of residents can make the park unsafe for those who wish to cause trouble.
Do like the returning vets did when they came home to a town in Tennessee that had been taken over by a criminal gang.
The returning vets went to the NG armory, got some weapons and proceeded to scour the town.
That is what it will take: angry locals scouring their town of the thug element.
(The Tenessee incident happened after WWII.)