An overnight explosion in the kitchen of the Santa Rita Jail has left eleven people injured, one of whom remains in critical condition.

Sources within the facility have said a total of four people were hospitalized as a result of the incident.  The remaining seven were treated on-site at the Santa Rita Jail infirmary.

The Alameda County Sheriff's Department said they are still looking into what caused the fire and explosion and are working with local fire investigators to get to the bottom of things.

What they do know, is the blaze originated in an oven, although it's not immediately clear whether the fire was sparked due to equipment malfunction or operator error.  Foul play has been ruled out, they said, but they are still trying to determine what exactly happened.

The force of that blast was so strong it blew a large steel door clear off its hinges.   Arson investigators and members of the bomb squad are examining all leads.

Ten inmates and one sheriff's deputy were hurt during the incident.  Those names have not yet been made public

Jail officials reportedly said the kitchen was badly damaged but was not destroyed entirely.   A spokesperson said additional information will be released to the public as it becomes available.