(Salem, OR) -- Oregon State Police are looking for witnesses following a collision on I-5 in Salem involving a bike and a car. It happened a week ago Sunday just before 4 a.m. north of the Highway 22 interchange. A white Subaru Outback was traveling northbound when it hit the bike. The rider was seriously injured. The driver stopped and cooperated with the investigation. Investigators think the bike was hit by another vehicle and they want to talk with that driver and anyone who witnessed the bike on the freeway before the crash.