A “freedom rally” in Portland, Ore., coordinated by the right-wing group Patriot Prayer was cut short Saturday after some of its supporters clashed with anti-fascist (antifa) counter-protesters.

The event began without incident until after 6 p.m., when members of Patriot Prayer took to the streets following their gathering in Portland's Terry Schrunk Federal Plaza, the Oregonian reported.

Patriot Prayer's organizer is Joey Gibson, a U.S. Senate candidate in Washington state, the newspaper reported, adding that the group is based in Vancouver, Wash., located just across the Columbia River from Portland.

Tensions escalated as the two groups heckled each other, the report said. Antifa members began lobbing eggs, half-empty water bottles, and firecrackers. Others in the crowd lit firecrackers and smoke bombs.

Police eventually declared the gathering a riot, revoked Gibson's permit, and ordered protesters to disperse. Police warned that non-compliance would lead to arrest.

Photos and videos posted on social media showed some participants bleeding from injuries.

Officers confiscated an unspecified number of weapons, including utility knives and chemical sprays, and made several "probable cause" arrests, according to reports.

The two groups clashed in similar circumstances in the same area June 3.

The clash coincided with protests held in multiple cities Saturday as hundreds of thousands of people protested the “zero tolerance” U.S. immigration policy.

The Associated Press contributed to this report.