Let's put some snipers on rooftops around the perimeter of this zone.
Give them orders to put a bullet in Raz's head and any others running around with guns in the zone
Then have some soldiers trained in city combat on the ready, after you kill Raz, tell them they have 15 minutes to put down their weapons and give themselves up.
If not the military is coming in with orders to kill anyone in the zone.
You do not want to just arrest people, groups like this as that accomplishes nothing.
You need to be as heavy handed as possible to send the message this shit will not be tolerated to the others.
They do this knowing nothing will happen to them.
You can't be letting groups just take over cities like this.