Police began moving in on a downtown park Sunday, where a few hundred Occupy Portland demonstrators have remained in defiance of an eviction order.
Police on loudspeakers warned that anyone who resisted risks arrest and "may also be subject to chemical agents and impact weapons." Demonstrators chanted "we are a peaceful protest."
Mayor Sam Adams had ordered the camp shut down last night, citing unhealthy conditions and the encampment's attraction of drug users and thieves.
The anti-Wall Street protesters and their supporters had flooded a city park area in Portland early Sunday in defiance of an eviction order while authorities in other cities stepped up pressure against demonstrators, arresting dozens of people.
Crowds converged on two adjacent downtown Portland parks where protesters are camped after city officials set a midnight Saturday deadline to disperse. Hours later protesters remained, though the crowd had thinned and obeyed police orders to clear the street and take down two makeshift barricades. At one point overnight, the crowd swelled to thousands.
As dawn arrived, riot police had retreated and most of the crowds had gone home, but protesters who have been at the two parks since Oct. 6 were still there.
One of the organizers, Jim Oliver, said the night had been a victory for Occupy Portland.
"We stood up to state power," Oliver told The Associated Press, standing on a corner opposite the camp.
Still, the camp is a shadow of what it was before Saturday. A large segment of the campers consisted of homeless people who had been drawn to the free food and shelter offered by Occupy Portland. They are gone, after outreach workers went through the camp to help them find shelter elsewhere. And as the Saturday midnight eviction deadline neared, protesters themselves began dismantling tents.
Around 4 a.m., dozens of police formed a line across from demonstrators who had poured into the street. Protesters facing them appeared to be in festive spirits with some banging on drums and plastic pails, another clanging a cowbell while others danced in the streets as a man juggled nearby.
Other demonstrators used pallets and old furniture, wood debris and even a bicycle to set up two makeshift barricades on a street that runs through the encampment, apparently in an attempt to block traffic.
Protesters ultimately got off the street after the police asked them to and also cleared away the barricades.
On Sunday at an impromptu news conference, the mayor defended his order to clear the park, saying it is his job to enforce the law and keep the peace. "This is not a game," Adams said.
He also noted that implementing the eviction order may require more patience.
"Giving the order that the parks will be closed to the public is putting my foot down. Enforcing will take time," he said.
Officials said that one officer suffered minor injuries when he was hit by some kind of projectile in the leg. Police had prepared for a possible clash, warning that dozens of anarchists may be planning a confrontation with authorities. Officers seized pieces of cement blocks Friday, saying they were told some demonstrators had plans to use them as weapons against police. They said they believe some demonstrators were building shields and trying to collect gas masks.
In the hours leading up to midnight, protesters held general assembly meetings where they talked about what to do when the deadline came. The also repeated the main message of Occupy Wall Street movement of peaceful resistance to income inequality and what they see as corporate greed.
As those speeches were going on, some snacked on coffee and burritos as others sang protest songs.
About 60 bicycle riders circled the camp repeatedly to show support.
"We are a peaceful resistance," said rider Chico Tallman, a 63-year-old accountant. "But we're fed up with the direction the country is going. It's all about profit."
For the second time in as many days, Oakland city officials warned protesters Saturday that they do not have the right to camp in the plaza in front of City Hall and face immediate arrest.
The eviction notices come as officials across the country urged an end to similar gatherings in the wake of three deaths in different cities, including two by gunfire.
Demands for Oakland protesters to pack up increased after a man was shot and killed Thursday near the encampment site.
"Your activities are injurious to health, obstruct the free use of property, interfering with the comfortable enjoyment of (Frank Ogawa Plaza), and unlawfully obstruct the free passage or use of a public park or square," the notice read.
Oakland officials first issued the eviction notice Friday after first pleading with protesters to leave the encampment.
Police officials have said a preliminary investigation suggested the shooting resulted from a fight between two groups of men at or near the encampment. Investigators do not know if the men in the fight were associated with Occupy Oakland, but protesters said there was no connection between the shooting and the camp.
The shooting occurred the same day a 35-year-old military veteran apparently committed suicide in a tent at a Burlington, Vt., Occupy encampment. Police said a preliminary investigation showed the veteran fatally shot himself in the head. They said the death raised questions about whether the protest would be allowed to continue.
In other cities:
— In Salt Lake City, police arrested 19 people Saturday when protesters refused to leave a park a day after a man as found dead inside his tent at the encampment. The arrests came after police moved into the park early in the evening where protesters had been ordered to leave by the end of the day. About 150 people had been living in the camp there for weeks.
— In Albany, N.Y., police arrested 24 Occupy Albany protesters after they defied an 11 p.m. curfew in a state-owned park. State police officials hauled away the protesters after warning them with megaphones that they were breaking the law in Lafayette Park. They were charged with trespassing.
— In Denver, authorities forced protesters to leave a downtown encampment and arrested four people for interfering with officers who removed illegally pitched tents, said police spokesman Sonny Jackson.
— In San Francisco, violence marked the protest Saturday where police said two demonstrators attacked two police officers in separate incidents during a march. Police spokesman Carlos Manfredi said a protester slashed an officer's hand with a pen knife while another protester shoved an officer, causing facial cuts. He said neither officer was seriously hurt, and the assailants couldn't be located.
Associated Press writers Terry Collins in Oakland, Josh Loftin in Salt Lake City, Jim Anderson in Denver and Andrew Dalton in Los Angeles contributed to this report.