Los Angeles Mayor Antonio Villaraigosa says he is empathetic to Occupy LA protesters and urges them to take alternatives to protesting on the lawn of City Hall.
Update at 8:55a.m. ET: NBC affiliate KNBC reported that at least five protesters were arrested early Monday after the 12:01 a.m. deadline imposed by city officials for Occupy Los Angeles to leave its tent-city passed.
Police Commander Smith said the encampment would be allowed to stay put until at least daybreak, according to Reuters, but he said protesters who block traffic had to move or face arrest.
"We have no plan at this time to go into the park and evict people," Smith said. "That could change in the near future, but right now we are hoping to clear the streets, and that'll be the end and people can relax for a little while."
Officers set up a perimeter around 1st and Main Streets as they started clearing the streets of protesters.
"Monday is a big traffic day, and there are thousands and thousands of workers who are trying to get to their jobs down here, so we really need to have these streets open," said Smith.
Update at 8:40a.m. ET: Police arrested three people early Monday after ordering Occupy Los Angeles protesters to leave a downtown intersection hours after a deadline passed to vacate a City Hall park encampment.
Water bottles were thrown at officers as officers in riot gear started clearing 1st and Main streets just after 5 a.m. PT Monday, the Associated Press reported.
The police department has been on tactical alert, meaning the late night watch was held over, since midnight.
At 4:50 a.m., police on loudspeakers declared an unlawful assembly and protesters were told to get out of the street within five minutes.
Commanders corralled demonstrators back to the City Hall park, telling them they won't be arrested there.
Earlier, a celebratory atmosphere filled the night outside City Hall and the encampment near it: a group of protesters on bicycles circled the block, one of them in a cow suit, while organizers led chants with a bull horn.
"The best way to keep a non-violent movement non-violent is to throw a party, and keep it festive and atmospheric," said Brian Masterson.
Shortly after the 12:01 a.m. PT Monday deadline, there was only a small police presence, about two dozen motorcycle officers who remained across the street from the camp.
Mayor Antonio Villaraigosa said earlier that the grounds would be closed after the deadline, while Police Chief Charlie Beck promised that arrests would eventually be made if protesters did not comply.
Villaraigosa said police and social workers will walk through the park handing out information on the closure and services available, and expressed hope it would happen in a "spirit of cooperation."
But many including the protest's chief organizers said they had no intention of cooperating, and only a handful of campers cleared out over the weekend.
Scott Shuster was one of those breaking down his camp, but he said it was only to protect his property and he planned to remain.
"I just don't want to lose my tent," he said.
Updated at 11:56 p.m. ET: Earlier, in Pennsylvania, a deadline set by the city for Occupy Philadelphia to leave the plaza it has occupied for some two months came and went without scuffles and arrests as police watched nearly 50 demonstrators lock arms and sit at the entrance of Dilworth Plaza.
The scene was far different from other, previous encampments in cities elsewhere where pepper spray, tear gas and police action resulted in the decampment of long-situated demonstrators, but Occupy Philadelphia has managed to avoid the mass arrests and conflict that has arisen at other sites nationwide.
Sunday night, there was hope that Philadelphia would continue to be largely violence-free.
"Right now, we have a peaceful demonstration," said Philadelphia Police Chief Inspector Joe Sullivan, nearly 45 minutes after the 5 p.m. deadline. By 11 p.m., the crowd had thinned a bit, but the calm remained.
Along the steps leading into a plaza, about 50 people sat in lines with the promise that they would not leave unless they were carried out by authorities. For a time, they linked arms. But as it seemed that a forceful ouster was not imminent, they relaxed a bit. A police presence was heavier than usual but no orders to leave had been issued.
A few dozen tents remained scattered on the plaza, along with trash, piles of dirty blankets and numerous signs reading, "You can't evict an idea."
Several hundred supporters surrounded those who were prepared to face arrest for one of the Occupy movement meetings known as a general assembly.
"There are some shelters that some of us are going to go to, some of us are going to end up on the street, some of us are going to be able to find a family member to take us in and others might go to jail," a protester told NBC Philadelphia.
"We can definitely claim a victory," said Mike Yaroschuk, who was in the process of dismantling his tent. "We've opened a lot of minds, hearts and eyes."
Yaroschuk said he was leaving the plaza not because of the city-issued deadline but because of a request by unions whose workers will be involved in the long-planned construction project there in the coming weeks. He said it made more sense to pick and choose when it comes to Occupy and its efforts to draw attention to the 99 percent.
"This place is not a key battle for me ... This is a marathon, not a sprint," he said.
Diane Ackerman, a member of the group's legal collective, said the movement itself will remain strong regardless of what happens. Occupy Philadelphia has been largely peaceful since it began. Despite a few dozen arrests, there have been no violent confrontations with police.
Philadelphia's eviction notice is unique in that protesters are being asked to move to make way for a construction project.