Hampton County sheriff's deputies were called at about 4:35 a.m. to a home on Pocotaligo Road in Yemassee to reports of a burglary in process.
Tamika Sylwanna Carter, 35, called 911 and said her estranged husband, Staff Sgt. Jerome Carter, 34, was trying to "enter her residence with force," said Capt. Anthony Russell of the Hampton County Sheriff's Office.
Russell said deputies arrived to find Jerome Carter lying in a hall with a gunshot wound to the chest.
No other injuries were reported.
Witnesses told authorities that Carter's alleged shooter drove off in a black Chevrolet Camaro and planned to turn himself into authorities.
Deputies were flagged down about five miles from the scene by the driver of the Camaro, Tusvon Jarell Russell, 26, of Varnville, who surrendered and was arrested, Capt. Russell said.
Capt. Russell did not say Monday whether Tusvon Russell had been charged in connection with the shooting or how he became involved in the incident involving Tamika and Jerome Carter.
Jerome Carter was transported to the Medical University of South Carolina in Charleston, where he was later pronounced dead, said Ernie Washington, Hampton County coroner.
The Hampton County Sheriff's Office is investigating, Capt. Russell said.
Cochran declined to provide details about his military service, citing a Department of Defense policy that prohibits the release of such information until 24 hours after the family of a deceased service member has been notified.
Those details will be released today, Cochran said.