WASHINGTON, April 16 (Xinhua) — Seven inmates have been killed and at least 17 others sustained serious injuries in a prison riot in the southeastern U.S. state of South Carolina, local media reported Monday.

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.

It's the latest violence in a system where 12 inmates were killed by other prisoners last year and 250 prisoners were assaulted so severely in 2016 and 2017 they had to be treated in outside hospitals, according to public records obtained by a Charleston newspaper columnist.

At the Bishopville prison where the seven were killed, one inmate held a guard hostage for 90 minutes in March and another killed a fellow prisoner in February.

Taillon said no officers were wounded after multiple inmate fights broke out at 7:15 p.m. Sunday. He said 17 inmates required medical attention outside the prison.