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.
Lee County Fire/Rescue said ambulances from at least seven jurisdictions lined up outside the prison to tend to the wounded. The local coroner’s office also responded.
The maximum-security facility in Bishopville houses about 1,500 inmates, some of South Carolina’s most violent and longest-serving offenders. Two officers were stabbed in a 2015 fight. One inmate killed another in February.