Seven inmates have been killed and at least 17 others seriously injured amid hours of fighting between prisoners inside a maximum security prison in the US State of South Carolina. Prisons spokesman Jeff Taillon announced the grim outcome after State Law Enforcement Division agents helped secure Lee Correctional Institution around 3 a.m. Monday. Taillon said no officers were wounded after multiple inmate fights broke out at 7:15 p.m. Sunday. He said 17 of the injured required medical attention outside the prison. The South Carolina Department of Corrections tweeted that it involved multiple inmate-on-inmate altercations in three housing units. Lee County Fire/Rescue said ambulances from multiple jurisdictions lined up outside to tend to the wounded. The local coroners office also responded. The maximum-security facility in Bishopville houses about 1,500 inmates, some of South Carolinas most violent and longest-serving offenders. In March, inmates at the prison held an officer hostage after taking control of a dorm room, US media reported. The inmates held the officer for about 25 minutes before the room was secured by law enforcement. In February, an inmate was killed by another prisoner in a fight. Two officers were stabbed in a 2015 fight.