Police in Portland, Oregon have arrested at least 13 people as a right-wing group marched to a downtown waterfront park and anti-fascist counter-protesters scuffled with officers who tried to keep the two sides apart.
A rally by hundreds of supporters of the right-wing Proud Boys organisation was met by a similar number of "Antifa" opponents, and isolated clashes broke out between both sides and between Antifa and police as the gathering wrapped up.
At least six people suffered minor injuries, according to police.
One person was taken to a hospital.
Officers said they seized weapons including chemical sprays, shields, metal and wooden poles, knives, and a stun gun from multiple groups.
Alt-right groups hold the End Domestic Terrorism rally at Tom McCall Waterfront Park in Portland, Oregon. Source: Getty Images North America
At the peak of the demonstrations there were an estimated 1,200 protesters on the streets of the downtown district, said Portland Police Chief Danielle Outlaw.
Charges against those in custody would include disorderly conduct, interfering with police, resisting arrest, and unlawful use of a weapon, she said at a news conference.
Right-wing and anti-fascist factions have clashed in Portland several times in recent months, including a rally that turned violent in July last year.
Hours ahead of Saturday's competing demonstrations, US President Donald Trump said: "major consideration" was being given to designating Antifa as a terrorist organisation.
"Portland is being watched very closely. Hopefully the Mayor will be able to properly do his job!" Trump wrote on Twitter.
The events began late in the morning.
Alt-right groups hold the End Domestic Terrorism rally at Tom McCall Waterfront Park in Portland, Oregon. Source: Getty Images North America
One person was injured and transported via ambulance, and three other people were evaluated by medics, Portland Police spokeswoman Lieutenant Tina Jones said.
The injuries were minor, she said.
Ms Jones said at one point there were about 1,200 on the streets, but that number had fallen to about 400 late in the afternoon.
An alt-right demonstrator is covered in mayonnaise after being chased by a group of counter-protesters. Source: Getty Images North America
Flag-waving members of the Proud Boys, Three Percenters militia group and others gathered downtown, some also wearing body armour and helmets.
Police said they had seized the weapons, including shields, from multiple groups as they assembled along the Willamette River, which runs through the city.
Members of Antifa hold up signs. Source: Getty
More than two dozen local, state and federal law enforcement agencies, including the FBI, were in the city for the right-wing rally that was expected to draw people from across the country.
Portland Police said all of the city's 1,000 officers would be on duty for the gathering that was hyped on social media and elsewhere for weeks.
In the days leading up to the event, Portland Mayor Ted Wheeler said people who espoused hate or engaged in violence were "not welcome."
Members of Antifa line up during an alt-right rally in Portland, Oregon. Source: Getty
Ted Wheeler, Portland's mayor, said he was not concerning himself with tweets from Washington, and he praised the response by law enforcement.
"I'm grateful that this was largely a peaceful event," Wheeler told reporters at the news conference.
"Police did an exemplary job of de-escalating the situation, keeping the extremists on both sides separated for the most part, and preventing people who wanted to engage in acts of violence from confronting each other."
