The riot started at about 9:30 p.m. Saturday at a block party outside of an apartment complex, The Bellingham (Wash.) Herald reported.
When police arrived, people leaving the party threw beer bottles and cans at officers, said Bellingham Police Lt. Mike Johnston.
Sam Kaplan, a Western Washington University sophomore who lives near where the riot took place, said a "parade of people" proceeded to an intersection and called more people out from parties nearby.
At about 11 p.m., after the crowd refused to disperse, police shot smoke grenades and "pepper balls" into the crowd, The Western Front, a campus newspaper, reported.
Multiple street signs were pulled down by rioters and police arrested at least two people.
The area was cleared by midnight.