The Pitchess Detention Center in Castaic reported an altercation between deputies and inmates, causing seven prison staff and two inmates to be hospitalised.
The incident began when staff were conducting security checks in the dorms at around 3.05pm when one of the inmates assaulted a deputy, according to officials.
More inmates became involved before deputies pepper sprayed 20-25 inmates.
The seven deputies and two inmates taken to hospital sustained non life threatening injuries.
Alejandra Parra, spokesperson for the Los Angeles County Sheriff’s Department, said there was an “inmate disturbance” in a dormitory.
The Los Angeles County Fire Department received reports of a medical emergency at 3.11pm, according to spokesperson Sean Ferguson.
Seven ambulances arrived on the scene.
The Pitchess Detention Center is currently on lockdown.