PORTLAND, Ore. » Anti-Wall Street protesters and their supporters flooded a city park area in Portland early Sunday in defiance of an eviction order, and authorities elsewhere stepped up pressure against the demonstrators, arresting nearly two dozen.

Crowds converged on two adjacent downtown Portland parks after city officials set a midnight Saturday deadline to disperse.

But nearly four hours later, the protesters were still there, backed by many supporters. Throngs spilled out into the streets adjacent to camp, tying up traffic.

At one point, protesters and their supporters swelled to thousands but those numbers started to thin in the early morning hours.

Organizers said they hope enough people will join them to make it difficult if not impossible for police to carry through on any eviction.

"Occupy the street," one organizer said through a bull horn. "Remain peaceful and aware. We have strength in holding the streets."

Some of the protesters referred to police in a chant: "Do not attack. We’re not violent."

Clusters of police with nightsticks and helmets were on hand, including some on horseback, but they weren’t taking any immediate action.

"We’ll take action that’s appropriate, when it’s appropriate," police spokesman Lt. Robert King told The Associated Press.

"We are not going to engage in confrontation for a misdemeanor," he said, noting that is the legal violation for remaining in the park after midnight.

It appeared earlier that about 200 campers planned to get arrested. But police action seemed less likely after the crowds swelled the parks in the early morning hours.

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 and discussed demonstrations to come. They stressed that Occupy Portland would not cease if and when the downtown camp was cleared.

As those speeches were going on, the mood turned festive at times inside the encampment with people snacking on coffee and burritos as others sang protest song and beat drums.

On Saturday, Occupy Portland protesters dismantled large sections of their encampment, but dozens of tents remained after midnight.

Mayor Sam Adams ordered the camp shut down, citing unhealthy conditions and the encampment’s attraction of drug users and thieves.

Demonstrators rallied Saturday evening as organizers said they hope radical elements don’t use violence to overshadow the movement’s message of peaceful resistance to income inequality and what they see as corporate greed.

But police 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 are building shields and trying to collect gas masks.

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 Salt Lake City, police arrested 19 people Saturday when protesters refused to leave a park a day after a man was 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.

Authorities in Denver 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.

Jackson said police had advised protesters since Wednesday that their tents in Civic Center Park and on a nearby sidewalk were illegal.

Violence marked the protest in San Francisco 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.

Meanwhile, in Southern California a small group of protesters braved soggy weather on Saturday to gather for the first time under the banner of Occupy Inland Empire. Members of Occupy movements in Fontana, Redlands, Riverside, and other nearby towns marched past banks and in front of San Bernardino City Hall in what they called a "visibility action," The Sun newspaper reported.