Someone vandalized the Portland Police union headquarters doing thousands of dollars in damage early Tuesday.
Spokesman Scott Westerman said just before 1 a.m., bricks and rocks were thrown through their windows, doing about $20,000 worth of damage to the outside of the building.
Eight people were arrested and three officers were injured Monday night when protesters clashed with police in downtown Portland in a rally against two recent officer-involved shootings.
Westerman said computers and other items were damaged inside the office.
No suspects have been named in the case.
A demonstration over a second fatal shooting by Portland police has resulted in charges against some protesters who confronted officers, a contrast to peaceful protests over a previous shooting.
At least eight protesters were arrested among the crowd of about 200 that marched through downtown streets Monday, protesting the shooting deaths of Jack Collins this month and Aaron Campbell in January.
Seven of them were arraigned Tuesday and one was cited after they were charged with disorderly conduct, criminal mischief and riot, according to Detective Mary Wheat, a Portland Police Bureau spokeswoman.
Wheat said four officers suffered minor injuries. The protest remains under investigation for other assaults against officers and additional property damage, she said.
The protesting group called itself Black Bloc and a number of them wore black masks or clothing as they chanted slogans, including "Cops, pigs, murderers" and "When cops attack, stand up, fight back."
The Black Bloc also posted advance plans for the protest on the Internet, with advice such as wearing protest clothing that could be easily discarded, chanting loudly and protecting protesters trying to damage property.
Police on foot, bicycles and horses tried to keep marchers on sidewalks as they walked through downtown on a route that took them past the federal courthouse and police headquarters before heading to the Portland State University campus.
A bank window was broken, and TV crews captured some protesters trying to vandalize TV trucks.
The protest was called to demonstrate against the March 22 shooting of Collins, a 58-year-old homeless man killed after officer Jason Walters responded to a report of a disturbance at the Hoyt Arboretum. Police said Collins was advancing on Walters with a knife and that the officer shot him after warning Collins.
Whitney Boise, the attorney for the officer, issued a statement Tuesday asking the public to withhold judgment until all the facts are known.
The other fatal shooting that led to the Monday protest was Jan. 29, when officer Ron Frashour killed Campbell in the parking lot of a Portland apartment building. A routine check on the welfare of Campbell, his girlfriend and some young children ended with Frashour shooting Campbell once in the back.
Police said Frashour, who is white, believed Campbell, who was black, was reaching into his waistband for a weapon but he was unarmed.
The shooting attracted national attention, including a visit by the Rev. Jesse Jackson, who called it "an execution."