DELANO, Calif. (AP) — An inmate was stabbed to death at a Central California prison, authorities said Monday.

Omar Orane, 40, was attacked by another inmate last Thursday morning at Kern Valley State Prison, according to a statement from the state Department of Corrections and Rehabilitation.

Guards used “chemical agents” to break up the attack, the statement said.

Orane was stabbed several times in the upper body with an inmate-made weapon and died at a hospital, authorities said.

Orane had been in prison since 2003. He was serving a 25-year sentence for second-degree robbery with use of a firearm in Los Angeles County. He was doing additional time for a 2016 conviction of possessing or making a deadly weapon while in prison.

Authorities allege that Orane’s attacker was Richard Escalon, 42, who was convicted of first-degree murder in Fresno County and in 2014 began serving a life sentence with the possibility of parole.

Kern Valley State Prison in Delano has more than 3,500 inmates, ranging from minimum to maximum security.