One soldier was injured Thursday morning after an explosion occurred inside the Demilitarized Zone (DMZ) separating the two Koreas, officials said.

The explosion took place at 9:20 a.m. on the western front of the DMZ in Paju, just northwest of Seoul, for unknown reasons, according to officials.

A 24-year-old Army staff sergeant, who was on a mission to detect land mines on the southern side of the inter-Korean border at the time, sustained what is presumed to be an ankle fracture due to the blast.

He was wearing anti-mine protective gear and sustained non-life-threatening injuries, officials said.

Military authorities are investigating the exact cause of the accident.