1. Let it fester for a few days. Be patient.
2. Then surround the place with seriously overwhelming military force. I’m talking thousands...
3. At the same time, shut off all water, electricity, cell towers, incoming foot or vehicle traffic. Nobody goes in or out period. Yes a few civilians might be uncomfortable.
Wait them out.
No food, no water, no utilities, no matter how many armed thugs they have at their fence, 3 of 4 days going hungry and they won’t have much fight left.
Then arrest every damn one of them.
My thoughts exactly. A few days of running their own pseudo-government, no food, water, outside help of any kind. Just don’t let them out to go get a Starbucks coffee. They will be killing each other in less than a week.