Two inmates killed a third inmate at a state prison in northeast California, officers stated Tuesday.

Prison staff stated they noticed Jose R. Castillo and Victor M. Zapien assault Richard Prieto in an train yard at Excessive Desert State Prison in Susanville Monday afternoon.

Correctional officers stopped the assault by firing a warning shot and chemical brokers however Prieto was pronounced lifeless quickly thereafter of puncture wounds to his chest, again, head and neck, state corrections officers stated.

Two inmate-made metallic weapons had been discovered on the scene, officers stated.

Prieto, 44, was serving a 22-year sentence from San Joaquin County for tried second-degree homicide.

Castillo, 26, was sentenced in Sonoma County to 6 years for assault with a lethal weapon on a primary responder, and an extra six years for possessing lethal weapon by a prisoner, authorities stated.

Zapien, 31, is serving a life sentence for a Stanislaus County homicide.

The prison in Lassen County homes greater than 3,100 inmates.