Updated at 3:20 p.m. ET
(CBS/AP) CHICAGO - Thousands of nurses and other protesters gathered Friday at a downtown Chicago plaza for a noisy but peaceful demonstration demanding a "Robin Hood" tax on banks' financial transactions, the largest protest yet ahead of a two-day NATO summit that is expected to draw even larger protests.
Members of National Nurses United, the nation's largest nurses union, were joined by members of the Occupy movement, unions and veterans at the rally city officials have said could attract more than 5,000 people because of a performance by former Rage Against the Machine guitarist Tom Morello, an activist who has played at many Occupy events. Early crowds did not appear to be that large.
The nurses and their supporters dressed in red shirts and wore green felt Robin Hood caps with red feathers.
Deb Holmes, a nurse at a hospital in Worcester, Mass., said she was advocating for the tax but also protesting proposals to cut back nurses' pensions.
"We've worked 30 years for them and don't want to get rid of them," she said.
"We bailed them out. As nurses, we are concerned because our patients are doing without medication. They do not have jobs. We bailed out Wall Street. It's time for them to give back to us," Dorothy Higgins, a nurse from Half Moon Bay, Calif., told CBS Chicago station WBBM-TV.
The rally which originally was scheduled to coincide with the start of the G-8 economic summit before it was moved from Chicago to Camp David drew a broad spectrum of causes, from anti-war activists to Occupy protesters to Cathy Christeller's nonprofit Chicago Women's AIDS project.
Christeller, the agency's executive director, said there is common ground among all protesters, even against the backdrop of the NATO summit.
"The whole ... idea we should slash the (social) safety net instituted here and in Europe It's a disaster," she said. "It ignores the source of the economic downturn, and it's making people suffer unnecessarily. This brings us together,"
Mary O'Sullivan and Chris Fogarty held the same signs that they carry every week. The retired couple have been protesting together for more than a decade, and Mary has carried the same sign for years, taping over "Honk to indict Bush" to read "Honk to indict banksters."
She said NATO "leaves rubble in their wake."
Ben Meyer, a Chicago lawyer who was observing the protest for the National Lawyers' Guild, denounced what he called an excessive police presence at the rally, which included dozens of officers milling through the crowd and lining the perimeter, some of whom were videotaping the rally.
"It's frustrating the state needs to come out and show this much force for a nurses' rally," he said. "They have everyone from the superintendent on down here. It's just ridiculous."
Chris Phillips, an Occupy activist from Buffalo, N.Y., said two police officers seized a wooden flag pole he was using to fly a flag reading "coexist" while standing on a bench on Daley Plaza. Officers told him the pole was considered a weapon.
"Did they read my flag? It's clearly a peaceful protest," he said. "I didn't hurt anybody. Are you kidding me?" Phillips said. He planned to protest nonstop for the next 4 days.
Meanwhile, lawyers for NATO summit protesters said police on Friday morning released four of nine activists arrested Wednesday on accusations that they had or planned to make Molotov cocktails.
The lawyers said police, with their guns drawn, raided an apartment building where activists were staying and arrested nine people. The Chicago chapter of the National Lawyers Guild said officers broke down doors in the building in the South Side Bridgeport neighborhood and produced no warrants.
"The nine have absolutely no idea what they're being charged with because they were not engaged in any criminal activity at all," said guild attorney Sarah Gelsomino. "They're really very confused and very frightened."
The Chicago Police Department refused to comment.
Many office buildings in the usually bustling Loop business district were closed after workers were warned to stay home because of heightened security, snarled transportation and the possibility of unruly protests.
Other small protests, including one targeting climate change, are also planned.
Shawmaf Khubba, a student at Montclair State University in New Jersey, took a 14-hour bus ride on Thursday with 40 others to join the Chicago protests. He said he wanted to raise awareness and tough questions about what he called NATO's unwarranted military aggression around the world.
"NATO is a strong arm of the U.S. that gives an excuse to go everywhere around the world," he said before Friday's rally. "I'm here because I care about what happens to people around the world."
Scattered protests over the past week have been relatively small, including a march through the "Magnificent Mile" shopping district that drew about 100 people Thursday.
"I think it's really going to be big ... with the nurses," Thayer said. "That is going to be the 99 percent staking itself against the 1 percent, drawing the connections between the war abroad and the war on working people here at home.
Estimates of how many might show up Sunday have varied widely, from a couple of thousand to more than 10,000. Busloads of demonstrators from around the country have begun arriving in Chicago, though some who had planned to come, including from the Occupy movement, have said they're staying home or going to an area near Camp David instead.
Police and the Secret Service have taken no chances, as heads of state from 50 countries begin arriving for the NATO summit, where leaders will discuss the war in Afghanistan and European missile defense.
Security is high on trains. Barricades and fences have been erected around landmark buildings. Streets are being closed. And world-class museums are shutting down.