A guard at a southwest Mississippi prison died Sunday and several other employees were injured during a disturbance involving hundreds of inmates that continued into the evening, authorities and the prison's operator said.

Emily Ham, a spokeswoman for the Adams County Sheriff's Office, confirmed Sunday evening that the guard died while being transported to a hospital. She said Corrections Corp. of America, the prison's private operator, was working Sunday night with law-enforcement authorities to bring the disturbance under control.

CCA said in a news release that the disturbance began at around 2:40 p.m. CDT. The news release said five employees were transported to a local hospital for treatment of injuries and one was taken offsite. It said "the disturbance is contained within the secure perimeter of the facility, with no threat to public safety."

State and local law-enforcement officers are providing outside perimeter security, the news release said.

The company said the cause of disturbance is pending investigation. The 2,567-bed prison houses adult male criminal aliens for the Federal Bureau of Prisons, the news release said.

CCA spokesman Steve Owen confirmed in an email "there has been one employee death" but he said he could not provide more details immediately.

"Efforts by facility staff and law enforcement officials to quell the incident are ongoing," Owens said in an email late Sunday to The Associated Press.

Ham said no inmates had escaped the facility.

Adams County Sheriff Chuck Mayfield told the Natchez Democrat that agencies were working to release eight staffers who were still inside. He said they know where some of them are and doesn't believe any more are injured. Fifteen employees were freed at once by opening a fence and protecting the route with guns, he told the newspaper.

Mayfield estimated that 200 to 300 inmates were causing the problems, including lighting a campfire. At one point, flames and smoke were visible from outside the prison. These inmates causing the troubles were not armed with traditional weapons, the sheriff said. Mayfield said the scene was calming down.