Two inmates armed with a homemade weapon attacked Robert Hargrave Thursday afternoon in a recreational yard at Kern Valley State Prison, according to a statement from the California Department of Corrections and Rehabilitation.

Guards ordered the prisoners to stop and then used what were described as chemical agents to break up the attack.

Inmate Dies at Hospital

Hargrave was stabbed in his back, chest, and abdomen and died at a hospital.

There was no immediate word on what spurred the attack.

Hargrave, 48, was serving a life sentence without the possibility of parole for first-degree murder in Riverside County. He came to the prison in 1994.

Alleged Attackers Identified

Two inmates are under investigation in connection with the killing, authorities said.

They were identified as Matthew Thornton, 38, who was admitted from San Diego County in 2009 to serve a 14-year sentence for attempted second-degree murder and Michael Arzaga, 47, who was received in 1998 from San Diego County to serve a life sentence with the possibility of parole for second-degree murder.