Another riot broke out in Portland late Tuesday as a mob broke into and set fire to a police union building.
Unrest in Oregon's largest city has unfolded nightly since late May.
The crowd of several hundred arrived outside the Portland Police Association's office and used vehicles and fencing to block off the road outside the building. Rioters started vandalizing the office with graffiti while others pulled plywood off of doors and windows.
Just after 11 p.m., several people began trying to break into the office. Portland police officers in the area told them to stop over loudspeaker, but the group ignored the police. The mob attacked a woman wearing an American flag as a cape when she tried putting out a fire they started next to the building.
Because of the efforts to break into the building and multiple fires, the Portland Police Bureau declared an unlawful assembly and ordered the crowd to leave the area.
As officers moved in to secure the building, rioters hurled projectiles like rocks and bricks, striking several officers. One officer was struck by an unknown alkaline substance, the bureau said in an incident summary.
A few blocks away, someone unleashed gunfire following a fight in the parking lot of a convenience store. Officers arrived at the location to investigate but left after finding no one was shot. Everyone present refused to speak to officers and the crowd chanted, "We don't need you." People threw items at officers as they drove away.
Rioters returned to the police union office and broke in around 1 a.m., inflicting damage and setting fire to the building, prompting officers to declare a riot.
Officers forcefully dispersed the crowd and most people left the area by 3:30 a.m. They used crowd-control munitions but not tear gas.
Those arrested were identified as Lisa Webb, 28, accused of rioting, disorderly conduct, and interfering with a police officer; Isaac Martin, 31, accused of attempting to assault an officer and interfering with an officer; and Carlton Smith, 47, accused of interfering with a police officer.
Portland officials have struggled to quell near-nightly violence since May. Rioters have regularly changed their targets, initially focusing on the Justice Center, a county building that houses a jail and a sheriff's office. They later turned to the Mark O. Hatfield Courthouse, a federal building. The Trump administration on July 4 sent federal assets to Portland because police failed to protect the building.
The union didn't respond to a request for comment. Daryl Turner, a police officer who heads the union, said last month that local leaders were at fault for not containing the unrest.
Kyle Shideler, director and senior analyst for Homeland Security and Counterterrorism for the Center for Security Policy, told officials that Antifa's goal "is to use physical violence and intimidation to terrorize American citizens to disengage them from the political process."
“Claiming that Antifa is too disorganized to understand should not be an acceptable excuse for law enforcement—federal, state, or local—to tolerate Antifa’s private street war to overthrow the constitution,” Shideler added later.
“Like their predecessors in the Weather Underground and Red Army Faction, Antifa will continue to escalate its behavior unless it is checked. There will be more attacks, and rioting techniques will continue to grow in capability and in sophistication, their cadres will grow, and there will be more autonomous zones for increased periods of time, and more Americans of all political persuasions will be terrorized."