A rally of far-right groups was met by a large counterdemonstration in Portland, Oregon, on Saturday.

Fears that the showdown would turn violent prompted some downtown businesses to close and led to a massive police presence. At least 13 people were arrested, according to Lt. Tina Jones of the Portland Police Bureau.

Six people, including one who was hospitalized, reported minor injuries during the day, police Chief Danielle Outlaw said at news conference.

There were also six "use-of-force" events by officers, she said, mostly involving "take-downs" of suspects, and no one was injured.

The dueling demonstrations garnered national attention, including from President Donald Trump, who tweeted earlier Saturday in reference to self-described anti-fascists, some of whom are known collectively as antifa, “Major consideration is being given to naming ANTIFA an “ORGANIZATION OF TERROR.” Portland is being watched very closely. Hopefully the Mayor will be able to properly do his job!”

Portland police tweeted about 30 minutes after the protests started at 11 a.m. that officers were there to protect people's right to speak freely.

“PPB and our partners are here to protect everyone's safety while facilitating everyone's 1st Amendment right to gather and speak. It is the foundation of our democracy and critical to Portland's identity,” police tweeted.

Officers worked to keep the opposing groups apart and nearly an hour after the demonstrations began police said they had seized weapons from participants including bear spray, shields, and poles.

#ppbalert Officers have seized weapons from multiple groups, including bear spray, shields, and metal and wooden poles. pic.twitter.com/NY2KEK8c8Y — Portland Police (@PortlandPolice) August 17, 2019

Authorities were also receiving reports of individuals carrying weapons and wearing protective equipment trying to infiltrate opposing groups at multiple locations.

The far-right demonstration was organized by members of the Proud Boys, whose founder has described it as a "fraternal organization" for young "Western chauvinist" men. The goal of the so-called "End Domestic Terrorism" rally, they said, was to get antifa, declared as a domestic terrorist organization.

The Proud Boys released a statement Saturday vowing to return to Portland monthly unless the mayor "takes charge and removes the scourge of violent domestic terrorists from his city," a reference to antifa demonstrators.

Mayor Ted Wheeler, a Democrat, said such far-right organizations were "impacting the entire nation" by targeting women, minorities and immigrants with hate speech.

"If they're going to come out here every single month until we do whatever they think" it would cost taxpayers millions of dollars for law enforcement, he said during the news conference.

The threat to return to Portland on a regular basis "feeds in to that sense of fear," Wheeler said.

"We do not want them here in my city, period," he said.

Members of the Proud Boys and other right-wing demonstrators march across the Hawthorne Bridge during a rally in Portland, Ore., on Aug. 17, 2019. The group includes organizer Joe Biggs, center in green hat, and Proud Boys Chairman Enrique Tarrio, holding megaphone. Noah Berger / AP

One antifa protester at the rally, Skyler, told MSNBC that she wants “to show is that the far right has no place in America.”

Police worked with dozens of other agencies at the local, state and federal levels to maintain control of the demonstrations.