Seven inmates were killed and 17 others were injured in an incident at Lee Correctional Institution in Bishopville, South Carolina, authorities said.
No officers were injured, said Jeffrey Taillon, communications director for the South Carolina Department of Corrections.
The incident started at 7:15 p.m. ET Sunday and involved “multiple inmate altercations in three housing units,” Taillon said. The facility was secured at 2:55 a.m. ET Monday.
No other details were given about what led to the fights.
Lee Correctional Institution, a maximum-security prison for men, has been the site of several other violent and deadly outbreaks this past year, CNN affiliate WACH reported.
Last month, inmates reportedly overpowered an officer for more than an hour and took control of one side of a housing unit.
In February, inmate Robert Odell Brown was killed by another inmate at Lee Correctional Institution.
Last November, another dispute between two prisoners led to the stabbing death of inmate Larry Rainey.
And last July, inmate Christian D. Ray died from injuries suffered during a fight.