Police in the US state of Oregon seized a number of weapons as hundreds of far-right protesters and counter-demonstrators rallied in the city of Portland on Saturday (local time).
The far-right rally was organised by the Proud Boys, classified by a major US civil rights organisation as a hate group.
The Proud Boys said the aim of gathering was to press for the anti-fascist group Antifa to be declared a domestic terror organisation.
Police set up concrete barriers and closed streets and bridges in an effort to contain and separate the rival groups, after seizing metal poles, bear spray, shields and other weapons.
The city’s mayor said the situation was “potentially dangerous and volatile” but by early afternoon, local time, most of the right-wing groups had left the area via a downtown bridge and police used officers on bikes and in riot gear to keep black-clad, helmeted and mask-wearing anti-fascist protesters from following them.
Police said they arrested 13 people amid skirmishes between the two groups throughout the day.
Police declared a gathering of mostly left-wing activists near Pioneer Courthouse Square a “civil disturbance” and told people to leave.
One person suffered minor injuries and was taken away by ambulance, while another three other people were evaluated by medics, a Portland Police spokeswoman said.
She said at one point there were about 1,200 people on the streets, but that number fell to about 400 late in the afternoon.
Flag-waving members of the Proud Boys and Three Percenters militia group gathered late in the morning, some also wearing body armour and helmets.
Police said they had seized the weapons from multiple groups as they assembled along the Willamette River, which runs through the city.
More than two dozen local, state and federal law enforcement agencies, including the FBI, were in the city.
The gathering was hyped on social media and elsewhere for weeks.
In the days leading up the event, Portland Mayor Ted Wheeler said people who espoused hate or engaged in violence were “not welcome.”
In a Saturday morning tweet, US President Donald Trump said “major consideration” was being given to naming Antifa “an organisation of terror”.
Mr Wheeler responded to the President’s tweet in an interview with CNN, saying: “Frankly, it’s not helpful”.
Mr Wheeler tied the demonstrations to “a rising white nationalist movement.”
“We’re certainly seeing that play out…Portland being a very progressive community is always going to be at or near ground zero of this battle,” he added.
There is currently no mechanism for the US government to declare a domestic organisation a terror group.
The State Department maintains a list of designated foreign terrorist organisations, such as Al Qaeda, but there is no comparable designation or list for American groups.