SHIRLEY, Mass. (AP) — Authorities say six Massachusetts inmates have been indicted on assault charges for an attack that left six correction officers injured at a state maximum-security prison.

Worcester County District Attorney Joseph Early Jr. identifies the inmates Friday as Kevin Semiglia, Buthchhay Chourb, Jacquan McKenzie, Tiberias Albert, Javante Antone and Jamaul Vital.

A surveillance video released by state officials shows an inmate approach the officer station on Monday and attack the officers before other inmates join the assault. It was first reported by WCVB-TV.

A Department of Correction spokesman says six officers were taken to the hospital and one was under a concussion protocol.

The prison remains on lockdown Friday.

NFL tight end Aaron Hernandez was serving a life sentence in a killing when he hanged himself in 2017 at the prison.