Prisoners took five hostages at a Delaware prison on Wednesday, later releasing one and entering into negotiations with state and federal authorities while continuing to hold the remaining four, police said.
All five hostages were state Department of Correction employees, and the one who was released was taken to the hospital with non-life-threatening injuries, Sgt. Richard Bratz, a spokesman for Delaware State Police, told a news conference.
Officials did not know if anyone else was injured at the James T. Vaughn Correctional Center in Smyrna, about 40 miles (64 km) south of Wilmington.
"Working with the Department of Correction, the FBI and the Delaware State Police will continue negotiations to obtain a peaceful and safe resolution," Sgt. Richard Bratz, a spokesman for the Delaware State Police, told a news conference.
A correction officer radioed for help around 10:32 a.m. (1532 GMT) from the C building, which houses more than 100 inmates, Bratz said.
Overall, the men's prison holds about 2,500 minimum, medium, and maximum security inmates, including pre-trial detainees and inmates sentenced to the death penalty, according to the prison's website. It is also where Delaware executions are carried out, the website said.
An aerial view of the prison showed about two dozen men standing in three groups on an open space of the prison's sprawling campus. It was not clear if the men were prisoners or law enforcement.
(Reporting by Laila Kearney, Daniel Trotta and Ian Simpson; Editing by Chris Reese)