A South Korean reserve soldier went on a shooting spree Wednesday, killing a fellow reservist and injuring four others before killing himself, an army official said.

The official, who spoke on condition of anonymity because of office rules, said the military is investigating but had no other initial details. South Korean media carried similar reports.

Shootings at military barracks by soldiers have happened with some frequency in recent years, raising worries about bullying and mental health conditions in the country's armed forces. But a shooting spree involving a reservist is unusual.

All able-bodied South Korean men must serve about two years of mandatory military service under a conscription system aimed at coping with threats from rival North Korea.

After finishing military duties, South Korean men are required to take annual military training involving shooting drills for several years.