SEATTLE (Reuters) – Dozens were arrested and many police injured in clashes around Seattle’s biggest Black Lives Matter protest in weeks on Saturday, police said, with a renewed energy sparked by violent clashes between activists and federal agents in nearby Portland, Oregon.

Police said officers used non-lethal weapons in attempts to disperse the thousands of marchers in the late afternoon after some protesters set fire to the construction site for a King County juvenile detention facility and courthouse.

By 10 p.m.(0500 GMT), police had “made 45 arrests in connection with today’s riot in the East Precinct,” the Seattle Police wrote in a Twitter post.

It said “21 officers sustained injuries after being struck by bricks, rocks mortars/other explosives. Most officers were able to return to duty. One was treated at a hospital for a knee injury.”

Earlier the police had said they were working to secure access for the city’s fire department to the blaze, which it said was started by about a dozen people who were part of a large group of demonstrators.

President Donald Trump said on Thursday that he expanded the deployment of federal police to Seattle, enraging local officials and igniting anger among protesters.

“We saw what was happening in Portland and we wanted to make sure in our city we were standing in solidarity with other moms,” said Lhorna Murray, who attended on behalf of the newly formed Wall of Moms Seattle, replicating a tactic from the Portland protests where mothers, dressed in yellow, form a human wall between protesters and law enforcement.

The tactics of federal officers in Portland have drawn the ire of local leaders and Democrats in Congress, who say those officers are using excessive force and complain of overreach by the Trump administration.

U.S. Attorney for the Western District of Washington Brian Moran said in a statement on Friday that federal agents are stationed in Seattle to protect federal properties and the work done in those buildings.

The Trump administration has also sent federal police to Chicago, Kansas City and Albuquerque, New Mexico, over the objections of those mayors.