OAKLAND, Calif. — Police in riot gear clashed with anti-Wall Street protesters overnight, firing tear gas and beanbag rounds at hundreds of demonstrators in Oakland and forcibly evicting and arresting more than 50 others in Atlanta.

The moves come as business owners, residents and officials in cities where encampments have sprouted up since the movement began last month are increasingly complaining about crime, sanitation problems and disruptions to business.

The encampments were empty in both cities today, as police stood guard nearby.

Overnight, the scenes in Oakland were chaotic, with officers firing tear gas and beanbag rounds over three hours as protesters tried to re-establish a tent camp outside city hall that they had been evicted from earlier Tuesday.

Officials complained about what they described as deteriorating safety, sanitation and health issues at the dismantled camp.

Acting Police Chief Howard Jordan told reporters at a late night news conference that authorities had no other choice, saying the protesters were throwing rocks and bottles at officers. City officials said two officers were injured.

“We had to deploy gas to stop the crowd,” he said, according to a KCBS report.

Police have denied reports that they used flash bang canisters to help break up the crowds, saying the loud noises came from large firecrackers thrown at police by protesters.

The chemical haze from the tear gas hung in the air for hours, new blasts clouding the air before the previous fog could dissipate. The number of protesters diminished with each round of tear gas.

Police estimated that there were roughly 1,000 demonstrators at the first clash. Nearly 100 people were arrested, mostly on suspicion of misdemeanor unlawful assembly and illegal camping.

Among the protesters were young adults, some riding bicycles, protecting themselves from the noxious fumes with bandanas and scarves wrapped around their faces. Protesters were still resolved to continue.

“This movement is more than just the people versus the police,” Mario Fernandez said. “It’s about the people trying to have their rights to basic services.” He added, “This crowd isn’t going anywhere anytime soon.”

In Atlanta, helicopters hovered and trained spotlights on the city’s downtown as police in riot gear moved into a small city park just after midnight and arrested protesters who had been there in tents for about two weeks.

Before police marched in, protesters were warned a couple times around midnight to vacate the park or risk arrest. Inside the park, the warnings were drowned out by drumbeats and chants of “Our park!”

Organizers had instructed participants to be peaceful if arrests came, and most were.

Many gathered in the center of the park, locking arms, and sang “We Shall Overcome,” until police led them out, one-by-one to waiting buses. Some were dragged out while others left on foot, handcuffed with plastic ties.

The police presence was “overkill,” said state Sen. Vincent Fort, who was among those arrested after coming to the park in support of the protesters. He called the camp “the most peaceful place in Georgia.”

“At the urging of the business community, he’s moving people out,” he said, referring to Mayor Kasim Reed. “Shame on him.”

Police included SWAT teams in riot gear, dozens of officers on motorcycles and several on horseback. By about 1:30 a.m. today the park was mostly cleared of protesters.

Reed said he was upset over an advertised hip-hop concert that he said drew 600 people to the park over the weekend but didn’t have a permit and didn’t have security guards to work the crowd, calling it irresponsible.

Reed said he had serious security concerns that he said were heightened Tuesday when a man was seen in the park with an assault rifle. He said authorities could not determine whether the gun was loaded, and were unable to get additional information about it.

An Associated Press reporter talked to the man with the gun slung across his back earlier Tuesday as he walked in the park. He wouldn’t give his name, but said he was an out-of-work accountant who doesn’t agree with the protesters’ views.

He said he was there, armed, because he wanted to protect the rights of people to protest.

There’s no law that prevents him from carrying the gun in public, but police followed him for about 10 minutes before moving off.

Across the country, complaints about crime and sanitation have been increasing as protesters prepare to settle in for the winter.

The mayor of Providence, R.I., is threatening to go to court within days to evict demonstrators from a park.

Businesses and residents near New York’s Zuccotti Park, the unofficial headquarters of the movement, are demanding something be done to discourage the hundreds of protesters from urinating in the street and making noise at all hours.

“A lot of tourists coming down from hotels are so disgusted and disappointed when they see this,” said Stacey Tzortzatos, manager of a sandwich shop near Zuccotti Park. “I hope for the sake of the city the mayor does close this down.”

She complained that the protesters who come in by the dozen to use her bathroom dislodged a sink and caused a flood, and that police barricades are preventing her normal lunch crowd from stopping by.

In Philadelphia, city officials have been waiting almost two weeks for Occupy Philly to respond to a letter containing a list of health and safety concerns. City Managing Director Richard Negrin said officials can’t wait much longer to address hazards such as smoking in tightly packed tents, camp layouts that hinder emergency access, and exposure to human waste.

“Every day that they haven’t addressed these public safety concerns simply increases the risk,” he said Tuesday.

Stephen Campbell, a protester in Boston, said the troublemakers are the minority.

“We have a policy here: no drugs, no alcohol,” he said. “Us occupiers really try to stick true to that. Other people who move in, who maybe have an alcohol problem or a drug problem, you know, we’re not fully equipped to handle things like that.”

In Minneapolis, Hennepin County Commissioner Jeff Johnson said some constituents who work downtown are getting a little tired of the piles of belongings cluttering the plaza, while others are worried about escalating costs.

The sheriff’s department has already spent more than $200,000, most of that in overtime.

Oakland officials had initially been supportive of the protests, with Mayor Jean Quan saying that sometimes “democracy is messy.”

But tensions reached a boiling point after a sexual assault, a severe beating and a fire were reported and paramedics were denied access to the camp, according to city officials. They also cited concerns about rats, fire hazards and public urination.

When police moved in, they were pelted with rocks, bottles and utensils from people in the camp’s kitchen area, but no injuries were reported. Protesters were taken away in plastic handcuffs, most of them arrested on suspicion of illegal lodging.

Protesters disputed the city’s claims about conditions at the camp.

Lauren Richardson, a college student from Oakland, said that volunteers collected garbage and recycling every six hours, that water was boiled before being used to wash dishes, and that rats had infested the park long before the camp went up.

“It was very neat. It was very organized,” Richardson said.

In New York, the neighborhood board voted Tuesday night to pass a resolution that proposed off-site portable bathrooms funded by local donors, said Julie Menin, head of the board. The resolution also requested that loud noises, like the blast of air horns and group chanting, be limited to two hours during the day.

The park’s owner, Brookfield Office Properties, tried to push the protesters out two weeks ago to clean it but backed off at the last minute after a public outcry.

Menin said the neighborhood does not believe the protesters should be kicked out. “We do not want the city to use force in any way,” she said. “And we think it’s possible to address quality-of-life issues.”

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