OAKLAND, Calif (Reuters) - Police arrested more than 100 demonstrators early on Thursday in clashes that activists and Oakland city officials alike blamed on agitators who provoked unrest following a day of mostly peaceful rallies against economic inequality.

Officials said eight people -- five civilians and three police officers -- were injured in violence that left Oakland streets littered with graffiti, smashed glass and debris. But the nature or severity of those injuries was not disclosed.

Busloads of police in riot gear advanced on demonstrators after midnight, firing tear gas to disperse hundreds lingering in downtown streets hours after protesters numbering in the thousands had forced a shutdown of the busy Port of Oakland.

The clampdown appeared aimed at preventing protesters from expanding their foothold in the streets around a public plaza that has become a hub for demonstrations in Oakland, a largely working-class city on the eastern banks of San Francisco Bay.

City officials said police acted in response to "a select group of people" who vandalized property, set several fires, assaulted police officers and broke into a downtown building.

"We had the opportunity to isolate the main group of people who seemed to be hiding in the crowd all day," Mayor Jean Quan told a news conference. "The police, I think, very effectively got in and surrounded and arrested them."

Activists from the Occupy Oakland movement, who are aligned with anti-Wall Street protests in New York and other U.S. cities against corporate excesses, high unemployment and bank bailouts, said the vandalism gave police an excuse to intervene. Some blamed "anarchist youths" for the unrest.

"Everything went beautiful until these guys (came) with scarves around their mouths, and then all hell broke loose. Our city just got demolished," said Johnny Allen, 60, a health-care provider sweeping away debris in front of City Hall.

City crews pressure-washed graffiti messages such as "kill cops" and "SMASH" that had been sprayed on downtown buildings.

Protester Laura Long said it was unfortunate the rallies in the city "should be marred by broken windows and graffiti."

Still, she called the police action "unprovoked."

Acting Oakland Police Chief Howard Jordan, addressing a special meeting of the city council on Thursday, said 101 people had been arrested.


Several hundred people attended the boisterous meeting, including protesters asking the city for more support and residents who backed them.

Business leaders called on the council to shut down the downtown protest encampment, saying it had damaged the local economy by driving customers away from stores and prompting new businesses to reconsider plans to relocate to Oakland.

"The situation we find ourselves in is absolutely unacceptable. We want Occupy Oakland closed," Oakland Metropolitan Chamber of Commerce president Joe Haraburda said, to boos and hisses from protesters in the audience.

The unrest in Oakland, which has shot to the forefront of nationwide Occupy Wall Street protests, came a week after former U.S. Marine Scott Olsen was badly injured in a previous clash between police and protesters.

The wounding of Olsen, an Iraq war veteran turned peace activist, appeared to galvanize Oakland's demonstrators and helped broaden their grievances to include police brutality.

Following a day of rallies that drew some 7,000 activists at their height, police sought shortly after midnight to pen demonstrators back inside Frank Ogawa Plaza, a square next to City Hall that protesters have for weeks used as a camp.

Despite some early sporadic vandalism, demonstrators on the scene said downtown streets were largely calm when police -- who had kept their distance throughout the day -- arrived and ordered the "unlawful assembly" to disperse.

Lined up shoulder to shoulder, police fired volleys of tear gas, forcing the demonstrators to retreat to the plaza, then made a second charge with batons and tear gas about an hour later to drive protesters farther into the square's interior.

Some protesters hurled tear gas canisters and rocks back at police. At least one was seen being carried away with a leg injury. Another who had been arrested, his hands bound behind him, lay on the ground with blood streaming down his face.

Adam Konner, 29, of Ann Arbor, Michigan, said he didn't clearly hear a police announcement ordering "campers to move back to your tents," before officers rushed in.

"I was trying to figure what they were saying. I was trying to figure out if I could go back into the plaza," he told Reuters, recounting being knocked to the ground and arrested.

The streets were calm by daylight. Dozens of tents remained standing in the plaza, and a cold drizzle dampened prospects for further disturbances later in the day.

The Port of Oakland, the nation's fourth busiest maritime container-cargo hub with $39 billion in yearly imports and exports, was back in full swing by late morning after being shut down by the protests on Wednesday.

Friction between some Occupy Oakland protesters seemed deepened by the unrest after disagreements flared overnight between a minority of protesters who set up trash-can barricades and others, often older demonstrators, who lectured about the need to keep protests peaceful.

A sign on a coffee shop with a shattered window offered an apology: "We're sorry. This does not represent us."

(Additional reporting by Noel Randewich, Dan Levine, Lisa Baertlein, Jim Christie and Dan Whitcomb; Writing by Steve Gorman; Editing by Cynthia Johnston and Todd Eastham)

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