Police say two groups of people leaving a festival in Seattle's Seward Park exchanged gunfire from their vehicles before one of them caused a collision that briefly shut down Interstate 5.

Seattle police say one man was shot in the shoulder and is expected to survive. Detective Jeff Kappel said officers were still searching for the other people involved in the shootout Sunday.

Authorities say one of the vehicles from the shootout collided with a minivan on Interstate 5, causing the van to flip. The Seattle Fire Department said firefighters extricated two women in their 20s, who were taken to a hospital.