What they are doing is committing arson and rioting. They should be arrested pathetic or not. Also when a bunch of them show up at the same time and do the same things that is evidence of organization. If caught in the act and given a choice between a possibility of a lot of hard time and giving up the organizers some of them will flip. It is worth doing.
They can be attacked on many fronts. Organized, paid “anarchist” is oxymoronic, a conflict in terms, and they know it. This discredits them in the eyes of their own. Split them off and isolate them for the ridicule they deserve.