The incident occurred on 17th Street and Pacific Avenue.
Police say the motorcyclist was headed southbound on Pacific Avenue when the person was hit by a car headed eastbound on 17th Street at about 9:35 p.m.
The driver of the car left the scene, and another car came and hit the motorcyclist.
That driver stayed at the scene.
A pair of cousins say they heard a crash while playing soccer.
When they went to the scene, they found the motorcyclist underneath the car.
The motorcyclist was taken to a hospital in unknown condition.