A 17-year-old died during Pennsylvania National Guard training at Fort Jackson in South Carolina

Training with her twin sister for the Pennsylvania National Guard, a 17-year-old died Thursday, five days after she collapsed during an exercise at Fort Jackson, S.C., according to several news outlets.

Officials at Fort Jackson and with the Pennsylvania National Guard have confirmed the death of Alyssa Cahoon, but did not offer details about the circumstances.

“It’s such a tragedy,” National Guard Capt. Travis Mueller said in an email to The Inquirer Saturday night, adding that Cahoon was a native of Wayne County, Pa.

“We are exceedingly heartbroken and saddened, especially for her sister who was in training with her, her parents and the whole Cahoon family.”

He said the Guard had assigned a “casualty assistance office” to provide help and aid to the family.

Columbia, S.C., TV station WLTX quoted Army officials as saying that after Cahoon collapsed during a physical training exercise, she was taken to an off-base hospital. She died five days later.

The station said an investigation into the cause of the death was underway.

Fort Jackson is the nation’s largest military training center. It boasts to trains about have the nation’s soldiers, and 60% of the women entering the service.