Jockey Abel Cedillo is off his mounts for the remainder of Thursday's program after being unseated in the third race.
Cedillo was aboard Governance, who appeared to jump a shadow and lose his stride. Cedillo was unseated and was struck by a trailing horse.
Cedillo was treated on the racetrack and was responsive to ambulance personnel, officials said. He was taken to a local hospital in Long Beach. Track officials said Cedillo complained of pain in an arm, a hip and a knee.
In the fifth race, Cedillo was booked to ride Destiny's Journey, who will be ridden by Heriberto Figueroa.