The move came as a continuation of almost nightly demonstrations since the death of George Floyd in May.

This footage, posted to Twitter, shows the fire burning outside the building and a second clip of protesters cheering as a fire truck arrives at the scene.

The Justice Center, located on Southwest 3rd Avenue, houses the Portland Police headquarters; central precinct, courtrooms and a detention center.

Police warned protesters gathered that they may be subject to tear gas if they interfered with firefighters extinguishing the flames.