Self-described “anti-fascists” (or “Antifa”) launched smoke bombs and other projectiles at Portland police officers and attacked photographers documenting their actions on Sunday, law enforcement officers said.

Left-wing agitators descended upon Portland in response to a “Patriot Prayer” rally on Sunday. Antifa members reportedly launched smoke bombs and other projectiles at police officers, who arrested at least seven people, according to the Portland Police Department, which documented the violence on Twitter. At least two police officers were injured in the violence.

Smoke bombs are being thrown at officers in waterfront park. — Portland Police (@PortlandPolice) September 10, 2017

Antifa is throwing irritant smoke and projectiles at police. — Portland Police (@PortlandPolice) September 10, 2017

Projectiles being thrown at officers; officers detaining several people. — Portland Police (@PortlandPolice) September 10, 2017

Protesters are loading slingshots. One officer injured; fire medics responding. — Portland Police (@PortlandPolice) September 10, 2017

Officers are reporting that photographers are being attacked by protesters. — Portland Police (@PortlandPolice) September 10, 2017

Second officer injured after being struck in face with projectile from protester. — Portland Police (@PortlandPolice) September 10, 2017

Police now have a total of 7 people in custody from today’s protest. — Portland Police (@PortlandPolice) September 10, 2017

Far-left agitators have repeatedly turned Portland into a literal political battlefield.

A left-wing rally on May 1 turned into a riot after anarchists started fires, damaged property and threw homemade explosives at police officers, resulting in 25 arrests. (RELATED: ‘Everyone Will Be Subject To Arrest’ — Portland Protest Turns Into Riot)

At a June 4 free speech rally in Portland, Antifa attacked free speech marchers and launched projectiles at them that “included urine and feces filled balloons, balloons with unknown chemicals, marbles, bricks and rocks,” the city’s police chief explained in a letter to the mayor afterwards. (RELATED: Pee-Filled Projectiles A Recurring Weapon Of Choice For ‘Anti-Fascists’)