Occupy San Francisco demonstrators clashed with police Wednesday night after they returned to Justin Herman Plaza following the clearing of their encampment by police in an early morning raid.

About a half dozen Occupy protesters were arrested and later released during the evening, but police eventually pulled back after demonstrators refused to leave the plaza. The group greeted the police retreat with cheers and chants of "our park" and "cops are the 99 percent."

"I feel like we're all refugees of the 1 percent and the police were trying to kick people out of a public space," said Michael Sampson, 25, who was part of the Occupy Oakland protest, as he set up a tent in the plaza. "This belongs to the people."

Demonstrator Amy Oh, 32, called Wednesday's activities a "partial victory."

"The problem with all the constant raids and evictions is that it distracts from our original purpose," said Oh, referring to the movement centered on the global frustration over major banks, multinational corporations and the economy.

Late Wednesday, occupiers had set up about four tents at the site of their former encampment but eventually took them all down. The number of protesters had dwindled to about 40, but police remained nearby.

Demonstrators were upset that police raided the Occupy SF camp at about 1:30 a.m. Wednesday, arresting 70 campers and protesters and clearing out the 2-month-old, 142-tent encampment.

At least three demonstrators were arrested Wednesday afternoon after they reportedly blocked traffic outside the Federal Reserve building on Market Street.

More than 100 police officers, along with sheriff's deputies, firefighters and public works crews, converged on the camp at the foot of Market Street early Wednesday and gave protesters five minutes to clear out. The city took action after police and city officials stopped being able to communicate with the protesters.

The 70 were arrested on suspicion of illegal lodging and camping in a public park. Two were also arrested on suspicion of felony assault on a police officer after they threw a metal chair at him, hitting him on his face shield and causing minor injuries, Officer Albie Esparza said.

Police moved in after Mayor Ed Lee gave up hope of negotiating a voluntary departure from the plaza with the leaderless Occupy movement. The mayor, who had said repeatedly that tents would not be allowed in the plaza, repeated that warning Wednesday and said he meant it.

Lee noted that the city had given the protesters repeated warnings to move somewhere else. He said the protests have cost the city $950,000.

Although protests will be allowed at the plaza, the tents won't rise again, Lee said. "Everyone in the city has the right to protest," Lee said. "But overnight sleeping will not be allowed."

A separate offer to move the encampment to a vacant lot owned by the school district near 16th and Mission streets is also off the table, Lee said.

Supporters and members of the encampment regrouped during the evening. They held a rally at about 5 p.m. and returned to their former campsite, intending to hold a meeting to discuss where they might next set up camp.

A large contingent of police arrived as the general assembly was getting started. They issued an order to disperse and police in riot gear encircled protesters on the plaza.

Police arrested two young men, including one who was injured, who were in the perimeter of the circle. They also arrested a man and a woman who tried to cut him free from hand bonds.

Protester Jed Holtzman, 34, said he thinks the police response was overblown.

"Given that it's a public park that's open, it is not only an overblown reaction, it is a 100 percent misplaced reaction," he said, pointing out that they were only there to have their general assembly. "If there were 10 folks in here having a picnic, do you think this would be happening?"