PORTLAND, ORE. >> Federal authorities today forced demonstrators away from a plaza near a federal building as dueling demonstrations in Portland by right-wing and left-wing protesters turned violent.

The area includes county and federal buildings and has been the site of numerous recent protests.

Department of Homeland Security officers moved through the plaza across from an 18-story federal building. A federal courthouse is also near that area.

The demonstration began at about noon near the Multnomah County Justice Center in Oregon’s biggest city, local media outlets reported. Demonstrators hurled rocks and other items at each other and got into fights. Streets were blocked amid the mayhem.

Images showed what appeared to be hundreds of people involved, many of them wearing helmets and carrying makeshift shields. Some demonstrators appeared to use pepper spray during clashes, and at least one person appeared to pull a gun. No arrests were reported.

The Justice Center in recent weeks has been the target of left-wing protesters mostly operating at night, when they frequently get into clashes with police. Saturday afternoon’s demonstrations spread to other areas as crowds marched.

Right-wing groups had announced a rally near the Justice Center Saturday afternoon that quickly drew counter demonstrators. The building houses a police precinct, police headquarters, a county jail and courtrooms and is next door to a federal courthouse that was targeted for weeks last month by left-wing protesters who clashed with federal agents dispatched to Portland to protect it.

The protesters at Saturday’s demonstration included the Proud Boys right-wing group and left-wing protest groups Democratic Socialists of America and Popular Mobilization, The Oregonian/OregonLive reported.

Portland police issued a warning about two hours after the demonstrations began, warning that officers were prepared to start using crowd control weapons if the violence did not end.

Violent demonstrations have gripped in Portland for months, following the police killing of George Floyd in Minneapolis police custody.

The afternoon clashes followed predawn clashes between police and about 200 left-wing protesters outside a different police precinct. President Donald Trump on Saturday morning tweeted: “Another bad night of Rioting in Portland, Oregon,”

Demonstrators hurled bottles and rocks at officers and pointed lasers at them, damaging police cars and causing minor injuries for several officers, Portland police said in a statement.

One protester was given medical treatment at the scene after he threw rocks at officers and was shot with what police described as a “sponge-tipped less-lethal round,” the statement said.

He was among nine people arrested. Three were charged with assault on a police officer.

Many of the protesters wore helmets, eye protection, gas masks and body armor and some carried homemade wooden shields, police said.

A demonstration Friday that went into Saturday morning came a day after protesters in Portland clashed with federal agents outside a U.S. Immigration and Customs Enforcement building.

People in a group of about 100 late Thursday and before dawn Friday sprayed the building with graffiti, hurled rocks and bottles at agents and shined laser lights at them, Portland police said.

The agents set off smoke or tear gas and used crowd control munitions to try to disperse the crowd. Three people were arrested.

Also Friday, a number of federal buildings across the city were closed as the FBI investigated a car bomb threat.