A California prison inmate died after being attacked by three other inmates at a facility in Monterey County on Sunday, authorities said.

Cory Benton, 40, who was serving a 25-year sentence for assault with a deadly weapon with gang enhancements, was stabbed multiple times at the Soledad Valley State Prison.

According to the Department of Corrections and Rehabilitation, three inmates, all of whom are serving life sentences, attacked Benton with an “inmate-manufactured” weapon – also known as a shiv or shank.

Benton died when en route to a medical facility, prison officials said.

The three suspects, Alberto Valades, 54, Jose Valle, 33, and Jimmy Martinez, 32, were moved into restrictive housing as authorities investigated the stabbing.

Martinez is serving a life sentence for a murder committed in Los Angeles County. Valades is serving life for an L.A. County robbery conviction that was his “third strike.”

Valle was sentenced to life in prison with the possibility of parole on a first-degree murder conviction in King’s County, California, officials said.

Soledad Valley State Prison houses 2,687 inmates and employs approximately 1,500 people.