The accident happened around 9 p.m. during the fourth race of the evening. Officials say one horse went down suddenly and the rider behind him didn't have time to react. His horse tripped over the first and the jockey was thrown onto the track. The first jockey to go down was treated at the scene and remained at the track Friday night.
Officials say accidents like this are common in the sport.
"It happens quite often, they train here quite a bit during the race season, our units respond often on riders who have collided, gone down, or for other various injuries," said Orange County Fire Authority Batt. Chief Anthony Espinosa.
Both jockeys involved in the accident are said to be very experienced. The track also said it always has paramedics on stand-by should occasions like this arise.
The races resumed after the track was cleared.