A correction officer was assaulted Friday afternoon at the Souza-Baranowski Correctional Center in Shirley, Massachusetts, according to a spokesman for the state Department of Corrections.
Officials said the officer was taken to a hospital following the incident, along with two other officers who responded to the alleged assault.
The officer was surrounded and assaulted by a number of inmates in the N1 general population housing unit, authorities said.
After one of the officers radioed for help, additional officers responded and secured the area. The prison was placed in lockdown during the incident.
Six inmates were removed from the unit due to the incidents, which officials described as a "serious assault."
The exact conditions of the officers involved was not immediately clear.
The Worcester District Attorney's office is handling the investigation.
Souza-Baranowski Correctional Center is a maximum-security prison with about 1,000 inmates. It is the newest state correctional facility in Massachusetts, having opened in 1998.
A number of other incidents have taken place at the prison. In August 2019, a corrections officer was assaulted and four other prison guards were hospitalized after an alleged assault by an inmate.
Six officers were injured in another incident in August 2018.
A riot broke out at the facility in January 2017 after dozens of inmates in the P-1 housing unit refused to return to their cells after an alleged fight between two suspected gang members. The riot resulted in the destruction of the entire housing unit.
On April 19, 2017, former New England Patriots star Aaron Hernandez died by suicide in his cell at the prison.