The explosion broke out at about 9:27 am local time (00:27 am GMT) at the military unit in Gimhae, around 310 km southeast of the capital Seoul, according to Xinhua.
It was reported that the explosion took place at an oil storage facility.
Three civilian inspectors were wounded and taken to a nearby hospital. Among them, one was classified as a serious but non-life-threatening injury.
No soldier was injured in the accident, the exact cause of which the military authorities were investigating.
SD/