UNITED NEWS INTERNATIONAL (UNI) — Hours of fighting inside a South Carolina prison left seven inmates dead.

The fights broke out Sunday night, April 15, but the state Department of Corrections says they weren’t brought under control until almost 3 o’clock Monday morning.

The department reports multiple inmate-on-inmate altercations inside three housing units at Lee Correctional Institution, a maximum-security prison northeast of Columbia.

Local media report assaults are common inside the facility, which houses some of South Carolina’s most violent offenders.

In addition to the seven fatalities, 17 inmates suffered injuries that required medical treatment.

Lee County Coroner Larry Logan told The Associated Press most were stabbed or slashed, but some were simply beaten.

He added, “How else are you going to die in prison? They don’t have guns.”

The official causes of death, however, have yet to be determined.

No prison staff or emergency responders were hurt in the incident.