The California Department of Corrections and Rehabilitation says nine inmates have been hospitalized with stab wounds, bullet wounds and blunt force trauma.  The department's Terry Thornton says the prison is on lockdown pending an investigation.

THORNTON:   "Prison staff investigates it. Every prison has an investigative services unit and they investigate any kind of crime.  They can be thought of as a police department within a prison.  Because, this may be a surprise to some people, but, just because people go to prison doesn't mean they stop committing crimes."

An investigator from the department will also investigate the officers' use of deadly force

The prison is in Folsom and houses 2,800 inmates. Thornton says most are maximum-security inmates who are serving long sentences or who have proved to be management problems at other institutions.