Portland Police declared a riot Saturday after tensions between the right-wing Patriot Prayer group and local anti-fascist activists came to a head and broke out in violence.

The afternoon began with a permitted rally at Terry Schrunk Federal Plaza organized by Joey Gibson, U.S. Senate candidate for Washington and leader of the right-wing, Vancouver-based group.

A counter-demonstration by masked local anti-fascist groups gathered nearby among a heavy police presence. Officers seized weapons such as utility knives, clubs and chemical sprays, detaining several protesters early on.

Portland Police made four arrests during the demonstrations, none of them connected to the events of the day.

Tusitala "Tiny" Toese, 22, and Donovon Flippo, 23, were arrested upon arriving at Terry Schrunk Plaza for an alleged assault in Portland earlier in the month.

Luiz Marquez, 46, was lodged in the Multnomah County Jail on charges of theft and assault for the June 3 protest that also saw four others arrested.

And Matthew Braddock, 37, was arrested on charges of robbery and assault for an investigation that began May 31.

Things turned ugly shortly after 6 p.m., when Patriot Prayer protesters spilled into Third Avenue to begin their permitted march through the streets of Portland.

Antifa, Patriot Prayer protests clash in Portland. Posted by The Oregonian on Saturday, June 30, 2018

Antifascist counter-demonstrators immediately began lobbing eggs, half-empty water bottles and firecrackers at the conservative marchers, prompting federal police to fire paintballs filled with pepper spray into the crowd.

Portland police said four people were struck by the projectiles and had to be taken to the hospital. An officer was also struck and taken to the hospital.

The two groups continued heckling each other even as police intervened.

The bureau declared a riot and revoked the march permit soon after police said they witnessed several instances of assault and other criminal activity.

Portland police closed Chapman and Lownsdale squares around the same time, according to a tweet sent out by the department. They ordered rioters to clear the area and warned that non-compliance would lead to arrest.

Patriot Prayer demonstrators gathered again at Terry Schrunk Plaza shortly after the order, several of them stranded as Gibson had arranged buses to shuttle supporters from a loading area in Vancouver. The first bus back to Vancouver was boarded just before 7:30 p.m.

The conservative demonstrators were irked that police did not do enough to protect them, shouting at Portland officers and black-clad anti-fascists alike as they returned to the plaza.

The Patriot Prayer rally began at 4 p.m.

Gibson's followers and anti-fascist counter-protesters alike arrived in the two blocks east of Portland City Hall hours ahead of time, heckling each other behind metal barriers set up by Federal Protective Service and Department of Homeland Security police.

The Patriot Prayer grouped numbered nearly 150, while the counter-demonstration boasted attendance at least twice that. Combined, the dueling protests were a fraction of an earlier march in support of immigrant children separated from their parents at the southern border.

That event tallied up to 5,000 attendees.

The conservative rally in the federal plaza was a typical affair for the Vancouver-based political figure.

Gibson said he wanted to "bring light into a city that's full of darkness," verbally bashing Portland Mayor Ted Wheeler and Oregon Gov. Kate Brown. Gibson is one of 13 candidates vying for the GOP nomination in the U.S. Senate race in Washington, according to Ballotpedia.

A group of die-hard supporters exploded in raucous cheers as Gibson delivered his speech, where he mentioned his Senate campaign only once near the end of his address.

Corlyn Voorhees of The Oregonian/OregonLive staff contributed to this report.

--Eder Campuzano | 503.221.4344

ecampuzano@oregonian.com