April 16 (UPI) -- Seven people died and at least 17 were hurt after clashes at a maximum security prison in South Carolina, following clashes that began Sunday and lasted into Monday, authorities said.
The South Carolina Department of Corrections said the fights broke out in three housing units. Three altercations occurred Sunday evening and lasted for nearly eight hours.
At least six emergency agencies responded to what was termed a "mass casualty incident."
The maximum-security facility houses 1,600 inmates in Bishopville, S.C., about 55 miles from Columbia, and holds South Carolina's most violent and longest-serving offenders.
Several violent incidents have occurred at the prison in recent years. An inmate died there last summer during another fight.
Authorities are trying to determine the cause of Sunday's clashes.