The explosion was reported at 11:39 a.m. in a kitchen at the jail located at 5325 Broder Blvd., Alameda County fire spokeswoman Aisha Knowles said.
Of the 11 people injured, seven were treated at the jail infirmary while four were taken to hospitals, Knowles said. One of the people suffered critical injuries in the explosion, she said.
The cause of the explosion is under investigation, Knowles said.
Santa Rita Jail is Alameda County's main jail and ranks as the third-largest jail in the state, according to county officials.