There were maybe a thousand protestors just kind of chilling around city hall when riot police started slowly pushing the crowds back with tear gas, shields and mace. I didn't see anyone rioting but there were a few people who were obviously trying to provoke a bigger confrontation with the police.
Occasionally the police would charge crowds without their shields and arrest whoever didn't get out of the street fast enough. I saw about five or six unarmed people with their hands in the air get thrown to the ground and beaten during these charges. I saw one police officer fire some sort of tear gas cannon directly into a girl's back from about 3 feet away as she was walking away. I also saw police beat and arrest numerous people who's only crime was shit talking them.
A teenager was shot in the head about 50 feet away from me which started a small stampede. I saw his feet as the body was loaded into the ambulance a few minutes later.
Some videos I took before and during the initial riot police push: