Three staff members are recovering after an inmate attacked them at the Supermax prison.
The Federal Bureau of Prisons said an inmate at the United States Penitentiary Administrative Maximum in Florence assaulted a staff member using a homemade weapon on Wednesday.
Guards were able to restrain the inmate. The inmate was not identified.
All three staffers were taken to area hospitals with non-life threatening injuries.
The Federal Bureau of Investigations is looking into the incident.
Supermax houses some of the country's most dangerous inmates, including terrorists believed to have been involved in various domestic terrorism attacks.