ATLANTA - With helicopters hovering overhead, police moved into a downtown Atlanta park and arrested around 50 Occupy Wall Street protesters who had been encamped there for about two weeks early Wednesday.

Like in many other cities, protesters had been camping in Woodruff Park to rally against what they see as corporate greed and a wide range of other economic issues.

Before police moved 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.

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

State Sen. Vincent Fort was among those arrested and had come to the park in support of the protesters in recent days. He said the police presence was "overkill."

"He's using all these resources ... This is the most peaceful place in Georgia," Fort said, referring to Atlanta Mayor Kasim Reed. "At the urging of the business community, he's moving people out. Shame on him."

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

Occupy Atlanta organizers said the demonstrators who were arrested would go before a judge Wednesday morning. They were planning a march from the park to the jail shortly before the court hearings.

"It's real simple: This is a crisis of priorities that this small group of campers ... is the greatest threat in this city. It's outrageous," said organizer Tim Franzen.

Reed on Monday said he planned to revoke the permit allowing Occupy Atlanta protesters to live in the park, but was vague about when that might come.

Late Tuesday, police started surrounding the park at a busy intersection, and some protesters gathered up their tents, pillows, sleeping bags and other belongings, saying they didn't want to lose them. Right after the order to leave, some did, standing outside the barricades.

Hundreds of others stood on Atlanta's famous Peachtree Street, booing police. They shouted "Shame!" and "Who do you protect? Who do you serve?"

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.

As police moved in, protesters chanted, "Who's park, our park," and "We are here, we are stronger, we can't take it any longer."

TV images showed the number of police far outnumbering the protesters.

In Oakland, Calif., police shot tear gas in response to rock throwing from some of the demonstrators who had gathered there, authorities said.