While on duty, a U.S. Marine was shot and killed at Marine Barracks Washington on Tuesday morning. D.C. police are investigating, and a Marine Corps spokesman said the gunshot wound was not self-inflicted.

WASHINGTON — D.C. police are investigating the death of a U.S. Marine who was shot and killed Tuesday morning at the Marine Barracks Washington as an apparent accident.

Police confirmed that 20-year-old Riley Kuznia was shot at about 5 a.m. while on duty inside the barracks on Capitol Hill.

It was not a self-inflicted gunshot wound, spokesman Marine Gunnery Sgt. John Jackson confirmed to WTOP. Police said it appeared that a gun accidentally discharged.

Markelle Kuznia, of Karlstad, Minnesota, told The Associated Press the Marine was her son. Kuznia said her son joined the Marines because “he felt it was his duty.”

Police said they are treating the fatal shooting as a death investigation, and added that there are no criminal charges being investigated at this point.

“The command’s priorities are to take care of the Marine’s family and friends,” said Col. Don Tomich, the barracks’ commanding officer, in a news release. “We want to ensure these personnel are being provided for during this challenging time.”

The Marine Barracks was founded in 1801 and is the oldest active Marine Corps post. A Marine survived a self-inflicted gunshot wound at the compound in June. Another Marine was fatally shot in the head at the compound in 2013.

WTOP’s Zeke Hartner and The Associated Press contributed to this report.