Two people were arrested, according to the Chicago Police Department. One of them was taken into custody on the Michigan Avenue bridge for alleged battery to a police officer, officials said. The other protester was released without being charged.
A protester tore a NATO sign from that Michigan Avenue Bridge and the group disrupted traffic along Michigan Avenue and other busy downtown streets. Police responded in plainclothes, daily uniforms and in riot gear.
"The cops, you know, swarmed into a corner and we were trying to stay away from that. We don't want to get arrested. Then I saw them take him away into the car," Violet Staley, protester, said.
"Hopefully it doesn't get too much worse in the next couple of days but you know, we'll see," Saffron Lehrer said.Those involved in the march said they are protesting NATO's involvement in Afghanistan.
Police used the river to break up the protesters, but through social media they were able to meet once again near the Federal Reserve.
By late Friday evening, protesters had gathered at Michigan and Congress in the South Loop where they fueled up on food. Then the demonstrators took up another cause across the street at the Congress Plaza Hotel, the backdrop of the longest strike in U.S. history. There they joined hotel workers on strike who want higher wages and health care benefits.
"They have been on strike for almost nine years, over 364 days a year in our Chicago winters, and they still refuse to honor the contract?" said Andy Manos, Occupy Chicago Labor Committee.
"I respect they come to support us," said Efrain Cortina, striking worker.
Thousands attend peaceful, organized nurses rally in Daley Plaza
Protesters involved in the downtown march had attended a noontime anti-NATO rally at Daley Plaza that was organized by National Nurses United. The nurses had a permit for the rally, but the march -- which was not affiliated with the nurses union -- did not.
Thousands of people attended the Daley Plaza rally, the first against the NATO summit, which runs May 20-21 at Chicago's McCormick Place.
The nurses had originally asked for a parade permit, but that was rejected by the city. To avoid a ticket, they kept to the sidewalks, wearing green felt hats and masks as symbols of their call for a "Robin Hood tax" on Wall Street. They believe if put in place, the tax could raise up to $350 billion every year, and they want that money to be available for jobs, health care, education and other basic needs and services.
"We want economic crises to come to an end we'd like to know all humanity served with healthcare," Nurse Dawn Peckler said.
They were joined by other protesters.
"It's time to take our wealth back. They steal from us. We'll steal from them," Brian Beane, Occupy Chicago, said.
Once they arrived at Daley Plaza, the rally was almost like a summer stage show. Nurses danced and sang and enjoyed what they consider their triumph over city hall.
"The mayor's office tried to shut this whole thing down," singer Tom Morello said. The former Rage Against the Machine guitarist joined in the nurses protest when Chicago City Hall said the nurses couldn't rally in Daley Plaza. They fought back and the city gave in. The show went on as they had planned.
Morello said Friday that someone should "put those NATO criminals in animal cages and crank Rage Against the Machine 24 hours a day."
Long-time activist Tom Hayden, one of the Chicago Eight, was part of the event.
"It's been forty four years since I had a permit to speak in Chicago," Hayden said.
Other groups, including the one who marched on downtown, attended the nurses rally. Plenty of police were present, too, but not in riot gear. ACLU monitors were present for the largely peaceful rally.
"That doesn't mean there won't be sporadic moments, but when the message is a message of great conflict in society, I think there is a greater likelihood for that kind of behavior. These messages aren't nearly controversial," Harvey Grossman, ACLU, said.
"You see how orderly we are. It was an overreaction. We did everything we were supposed to," Deb President, nurse, said.
There was an incident at the conclusion of the rally where police sought to question a protestor they believed may have been carrying some sort of weapon. He refused to talk to them, which led to some pushing, shoving and taunts aimed at police.
The superintendent says the man was not charged, and the event was arrest free.
"They did a great job in keeping their organization organized. They did everything they needed to do. We did everything that we needed to do," Supt Garry McCarthy said.
Police estimate 2,400-2,800 people attended the rally.