But tensions reached a boiling point after a sexual assault, a severe beating and a fire were reported and paramedics were denied access to the camp, according to city officials. They also cited concerns about rats, fire hazards and public urination.
Demonstrators disputed the city's claims, saying that volunteers collect garbage and recycling every six hours, that water is boiled before being used to wash dishes and that rats have long infested the park.
When riot gear-clad police moved in early Tuesday, they were pelted with rocks, bottles and utensils from people in the camp's kitchen area. They emptied the camp near city hall of people, and barricaded the plaza.
Protesters were taken away in plastic handcuffs, most of them arrested on suspicion of illegal lodging.
Demonstrators returned later in the day to march and retake the plaza. They were met by police officers in riot gear. Several small skirmishes broke out and officers cleared the area by firing tear gas.
The scene repeated itself several times just a few blocks away in front of the plaza.
Tensions would build as protesters edged ever closer to the police line and reach a breaking point with a demonstrator hurling a bottle or rock, prompting police to respond with another round of gas.
The chemical haze hung in the air for hours, new blasts clouding the air before the previous fog could dissipate.