Eight protesters were arrested Saturday after a pre-dawn raid on the Occupy D.C. camp in McPherson Square, with dozens of police clearing away tents, bedding and dead rodents.

U.S. Park Police — on horseback and on foot with riot gear — swept into the park just after 5:30 a.m. A helicopter circled overhead, horses’ hooves clattered on the pavement and protesters ran through the camp trying to wake up those still sleeping.

Streets within two blocks of the downtown park were shut down because of the raid, which was characterized as “further enforcement” of a no-camping crackdown that began Monday.

There were tense moments. Late in the afternoon, a police officer was struck in the face by a thrown brick. A man was taken into custody in connection with the incident.

In McPherson Square, where protesters once slept, ate hot meals and snuggled in friendly “cuddle puddles,” they can now stay overnight only if they stay awake, keeping only unfurnished tents for the purpose of a round-the-clock vigil, police said.

“They can have the tents for symbolic purposes only. So long as there is compliance, we will have no issues,” said Sgt. David Schlosser, a Park Police spokesman. “Their First Amendment rights are paramount.”

Protesters and police at first interacted in good humor Saturday as they negotiated taking down the big, blue “Tent of Dreams,” which protesters had unfurled over a Civil War statue Monday. But relations grew tense as the day wore on and police began clearing the park of several truckloads of bedding and trash. At one point, dozens of officers pushed back the crowd with riot shields so they could erect more barricades.

“We’re being evicted without tear gas,” said Melissa Byrne, a protester from the District.

Schlosser said that police had moved in to do temporary “nuisance abatement” and that cleaning crews had found health hazards that included filthy bedding, bottles full of urine and several dead rats.

Four people were arrested when they refused to leave an area where the cleanup was underway, and they were charged with failing to obey a lawful order. Three others were arrested later and charged with crossing a police line.

Occupy protesters, demonstrating against economic inequality, have been living in McPherson Square and a similar camp at Freedom Plaza since October. But they have been criticized in recent weeks by congressional Republicans and District officials concerned about health, safety and cost issues.

After the National Park Service announced a week ago that it would begin enforcing the longtime camping regulations, protesters were told that they could not have overnight gear or sleep at the park, prompting some to go on “sleep strikes.” But while some complied with the rules over the past week, others remained encamped at McPherson.

Ann Wilcox, a member of the National Lawyers Guild who serves as a volunteer legal adviser to the group, said that although the pace may be slower, what is happening at McPherson is little different from high-profile Occupy closures at New York’s Zuccotti Park and elsewhere.

“They want the park to be clear in the coming days, and they’re going to keep checking back so [protesters] can’t reestablish themselves,” she said.

Frictions between protesters and police appeared to heighten Saturday when officers began a tent-by-tent search, tearing down some structures and throwing out bedding and belongings inside. Officers in yellow hazardous-materials suits and masks used poles to gingerly pick up used blankets, clothes and assorted debris and drop them into trash bags.

Cleanup crews uncovered dead rats and mice after removing wooden pallets that Occupiers used for sleeping.

Protesters became angry when it appeared that Park Police were tearing down tents without bedding, which they believed met the definition of “vigil tents” permitted by the National Park Service.

“Why are you taking down a tent with nothing inside of it?” protester Sara Shaw hollered from atop a park bench.

Capt. Philip J. Beck tried to calm the situation, noting that the Occupiers were allowed to videotape the cleanup efforts. “We’re not hiding anything. We’re not keeping anything about this a secret,” Beck said.

Beck said protesters whose tents were seized could pick them up Monday at the Park Police station on Ohio Drive SW.

Protesters said they had expected the raid, but some were surprised at the magnitude. It included dozens of officers, a patrol wagon, an arrest-processing tent and a cherry-picker truck used to remove the Guy Fawkes mask that had been placed over the face of Civil War general James B. McPherson’s statue.

“It’s pretty excessive,” said Ricky Lehner, a protester.

Mark Francis Nickens, a local musician who built a teepee in the square, said he watched helplessly from behind the barricades as police tore it down and threw out his dream catchers and poster of Sitting Bull. He hoped he would be able to recover three bags of clothes, but he wasn’t sure.

“I watched them take it down and felt they were taking something quite beautiful,” he said of his tent. As for the camp as a whole, he said: “I think it’s over.”

Staff writers Michael Bolden, Carol Morello, Martin Weil and Clarence Williams contributed to this report.