The controversial verdict has sparked waves of protests with scenes turning violent in some states.
A demonstration of about 200 people in Portland was declared a riot after protestors started breaking windows and throwing objects at police.
Reports claim that some rioters even talked about burning down the Justice Centre.
It come as Kyle Rittenhouse, 18, was acquitted of first-degree murder and four other charges on Friday night after he fatally shot two people and injured another during demonstrations in Kenosha.
“Due to violent, destructive behavior by a significant part of the crowd, the gathering in downtown Portland is a RIOT. All participants are instructed to proceed away to the WEST,” the Portland Police Bureau wrote on Twitter.
Chaotic scenes were also seen in Chicago with looters breaking into local shops.
Protestors have also been seen marching on the streets of New York but the situation has remained largely peaceful.
People rally in Portland following the Rittenhouse verdict
A small fire broke out near the Justice Center amid riots in Portland, Oregon
President Biden released a statement saying the Rittenhouse verdict “will leave many Americans feeling angry and concerned, myself included.”