They let the majority of the people just go home after some time. With the exception of those that commited criminal offenses. Like attacking policemen.

If a cop gets a hangnail while beating a protestor, they’ll say it was the protestor’s fault and charge them with assaulting an officer. They have charged people for breaking a cop’s hand, after the cop punched them in the face. I remember when I heard an old retired cop say that he and his buddies would knee someone in the balls, then refer to it in their reports as “the suspect violently groined my knee”.