A maximum-security federal prison known for housing the "worst of the worst" of the nation's criminals is looking into the apparent beating death of a 64-year-old inmate.

Fellow prisoners at the ADX facility near Florence, often called "Supermax," allegedly attacked Manuel Torrez at the prison Thursday morning.

Prison staff and medical personnel tried for about 20 minutes to resuscitate Torrez, but he was pronounced dead at a nearby hospital.

Fremont County Coroner Dorothy Twellman says Torrez endured a "vicious" beating, suffering severe injuries to his face, neck and chest.

It's the first alleged killing of a prisoner at the hands of other inmates in Supermax history.

Prison spokeswoman Wendy Montgomery declined comment.