Clearing out an encampment in a central city park, police fired pepper spray and pepper balls into an unruly crowd, and used batons to clear out others. The confrontations between Denver police and protesters gathered in support of Occupy Wall Street were among the most violent since Oakland police fired tear gas on protesters, critically injuring an Iraq war vet.

The Denver clash, happening on a Saturday afternoon as east coast media outlets braced for snow and storm conditions, nonetheless made national news. It was a chaotic scene, as police made one initial push into encampments near the state Capitol, and arrested five people after one police officer was knocked from his motorcycle, the Denver Post reported:

Protesters there surged around about eight police officers. Other officers responding to calls for help fired the pepper bullets, which resemble paint balls. One protester filming the scene — one of hundreds of cameras documenting police activity — was knocked out of a tree in the melee.

Five people were arrested in the first conflict, before 3 p.m. Hundreds of officers and SWAT members converged on the park, and Broadway was shut down for hours as police and protesters reached a tense stalemate.

About a dozen of the angriest marchers stood nose-to-nose with police and screamed profanities or anti-Wall Street slogans. Others tried to calm the situation, even while filming.

A little while later, the Post reported, police donned gas masks and began warning protesters over megaphones to break down their tents. Then officers wielding batons moved in to remove the tents. 

University of Colorado student Daniel Ellen tried to jump through a gap to help other protesters he feared were stuck in the tents but was knocked to the ground by police. He stood up and charged at them again, screaming in anger, took a blow to the temple with a baton and was pushed down twice more.

"I support the people here who are unemployed," said Ellen, who said adrenaline kicked in and he grabbed one of the batons before getting knocked back again. While the crowd surged around the officers, a Hare Krishna group chanted and danced just behind them.

Denver police said officers had acted responsibly. "All we did was take down the structures," a spokesman told the Post. "We're reacting to what they do. As long as they are legally protesting, we'll protect their right to do that. The officers today did a great job of showing restraint."

Protesters disagreed. One, Chantrell Smiley, of Denver, told the Associated Press she had been sleeping downtown in the park for more than a week with other protesters.

She said she didn't see the officer get knocked from his motorcycle and didn't see any reason for the afternoon confrontation.

"It was just chaos. This wasn't necessary. My friend got hit with rubber bullets in the face. He was screaming and bleeding, then they Maced him. We're being peaceful. We don't want to be harmed. They came through and took everything down — our food, our blankets, everything's gone."

There were arrests in other cities, including Portland, Ore., where protesters marched into the upscale Pearl District and refused to leave a park when ordered to do so by police. But those arrests occurred without violence, with protesters simply going limp and being dragged to waiting police vans, CBS News reported.