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Authorities asked protesters near the Portland Police Association office to leave Saturday night or risk arrest.
"This event has been declared a riot. Move to the east now. If you do not move to the east you will be subject to arrest or use of force to include crowd control munitions. Leave the area now," the Portland Police Bureau tweeted. It said protesters broke into the Portland Police Association office and set it on fire.
In a separate protest near the federal building downtown, protesters could be seen dismantling a heavy metal fence set up around the building earlier as a barricade.
Just hours earlier, police said the Federal Protective Service will not work in the Portland Police Bureau's incident command center after masked, camouflaged federal officers without identification badges arrested people protesting racial inequality in the city.
The Federal Protective Service will not use its command center starting Saturday night, according to Portland police.
During protests on Friday night, Portland officers and other law enforcement officers, including those from federal agencies, worked together to respond to disperse crowds, Portland police said in a statement. The federal officers worked under their own supervision and direction, according to the statement.
Seven people were arrested after people took a fence and barricaded the federal justice center, blocked streets, refused to disperse and threw projectiles at officers, police said.
The U.S. Attorney for the Oregon District has asked for an investigation into the incident involving the federal authorities.
The request is aimed specifically at the Department of Homeland Security personnel who have been captured on various videos arresting protesters and putting them in unmarked SUVs.
Ongoing protests in Portland
Demonstrators in Portland have been protesting racial inequality and police brutality for the past 50 nights, U.S. Attorney Billy J. Williams said in a statement. Federal authorities have protected the Mark O. Hatfield U.S. Courthouse and, at times, interaction between protesters and law enforcement has gotten violent. Last weekend, one protester was seriously injured after the man was shot in the head with impact munition.
Oregon's governor and Portland's mayor demanded the federal officers be withdrawn and a U.S. senator joined them in condemning the arrests.
"Authoritarian governments, not democratic republics, send unmarked authorities after protesters," tweeted U.S. Sen. Jeff Merkley, a Democrat representing Oregon.
Merkley also tweeted one video of such an arrest showing two masked, camouflaged individuals with generic "police" patches detain a person dressed in a black outfit and place them in an unmarked van before driving away.
U.S. Customs and Border Protection admitted to being one of the agencies involved in arresting protesters.
"Violent anarchists have organized events in Portland over the last several weeks with willful intent to damage and destroy federal property, as well as, injure federal officers and agents," the agency said in a statement to CNN. "These criminal actions will not be tolerated."
The statement said CBP agents suspected the individual seen in the video Merkley retweeted of "assaults against federal agents or destruction of federal property," and that they moved the individual to a safer location for questioning after they saw "a large and violent mob move towards" them. CNN could not independently verify what happened before or after the video was recorded.
Portland mayor: 'Not the America we want'
CBP Commissioner Mark Morgan tweeted the agency will continue to arrest "violent criminals that are destroying federal property." He also said CBP personnel are clearly marked as federal officers and have unique identifiers.
"You will not see names on their uniforms b/c these same violent criminals use this information to target them & their families, putting both at risk. As Acting Commissioner, I will not let that happen!" Morgan tweeted.
Portland Mayor Ted Wheeler demanded Friday that President Donald Trump send the federal agents home.
"This is not the America we want. This is not the Portland we want," Wheeler said at a news conference. "We're demanding that the president remove these additional troops that he sent to our city. It is not helping to contain or de-escalate the situation it's obviously having exactly the opposite impact.
Acting DHS Secretary Chad Wolf, who visited the city Thursday, defended the actions of his officers, saying in a tweet, "DHS officers were assaulted with lasers and frozen water bottles from violent criminals attempting to tear down federal property. 2 officers were injured."
"Our men and women in uniform are patriots," he said in another tweet that featured uniformed officers who looked to be similar to the ones shown in the video from earlier in the week.
In addition to U.S. Attorney Williams' call for an investigation, Oregon Attorney General Ellen Rosenblum filed a complaint in federal court Friday against DHS. The suit asks a judge to declare the federal officers' actions unlawful, and for an injunction requiring federal officers to identify themselves and their agency before detaining anyone in Oregon, and prohibiting them from arresting anyone without probable cause or a warrant.
Oregon Gov. Kate Brown described the arrests as "a blatant abuse of power by the federal government" in a tweet Thursday.
Brown tweeted she told Wolf "that the federal government should remove all federal officers from our streets."
"His response showed me he is on a mission to provoke confrontation for political purposes," she tweeted. "He is putting both Oregonians and local law enforcement officers in harm's way."