The explosion occurred at a South Korean military artillery unit in Paju City, northwest of the country, on the afternoon of September 10.
The blast injured at least eight soldiers, including two in critical condition.
According to South Korean officials, the explosion occurred at around 3:30 p.m. local time during an artillery exercise at the unit.
A shell used to create an explosive sound effect is believed to have exploded during the exercise.
South Korean military officials are investigating the incident.
