Three South Korean military officers were injured Monday in an explosion south of the heavily fortified border with North Korea, according to Seoul’s Joint Chiefs of Staff (JCS).

The military said in a statement that the officers “were injured by an unidentified explosion” while carrying out an operation south of the Military Demarcation Line (MDL) in the western front of the Demilitarized Zone (DMZ).

Two of the officers were urgently evacuated by helicopter to the Armed Forces Capital Hospital in Seongnam, where they are currently receiving treatment, the JCS said. 

The third officer is scheduled to be transported to the