A South Korean soldier looks at a North Korean military post while standing guard at the border village of Panmunjom, which has separated the two Koreas since the Korean War, in Paju, South Korea on March 12.
A South Korean sergeant killed five fellow soldiers, and wounded another seven at the country's border with North Korea on Saturday, local media reported.
Armed with a weapon, the solder is still at large, according to The New York Times. He launched his attack with a rifle at a military station in the province of Gangwon, east of South Korea's capital of Seoul. Authorities have not yet released his name.
Tensions between South Korea and North Korea have ratcheted up in recent months, but there is reportedly no evidence that North Korea was involved in the assault, according to the Associated Press.
Thousands of soldiers from South Korea and North Korea are stationed along the border between the two countries, as they have technically been at war since 1950. The Korean War subsided in 1953 after the two sides agreed to an armistice, which is an agreement to stop fighting but not to formally end a war.
Ships from both countries recently exchanged fire near a disputed border in the Yellow Sea, and North Korea has recently conducted a series of military drills to portray the strength of its armed forces, Reuters reported.
Similar single-soldier rampages are not unheard of in the South Korean military, according to the AP.
A marine corporal killed four comrades in 2011 at a military outpost on Ganghwa Island, according to the Times. He had reportedly shown signs of mental illness beforehand.
Another soldier used his gun and a grenade to kill eight fellow soldiers, and injure several others in 2005. He was reportedly upset because he felt higher-ranking officers had verbally disparaged him.
The South Korean military has tried to change its sometimes brutal culture since the shooting in 2011, when the Defense Ministry reportedly announced a new policy against beatings in the military.