Firefighters were called about 8:40 p.m. Thursday for a large animal rescue, the fire department said in a series of tweets.
The rider of the horse had minor injuries but the horse did not survive, the fire department said.
Access to the scene was limited and crews had to find creative ways to transport equipment to set up for rescue operations, the department said. East Bay Regional Parks police and the Alameda County Sheriff's Office were also involved, the fire department said.