Four North Korean soldiers fired about 40 rounds at a comrade fleeing into South Korea and hit him five times in the first shooting at the jointly controlled area of the heavily fortified border in more than 30 years, the South's military said Tuesday.
The soldier, whose rank and identity have not been disclosed, was flown by helicopter to hospital on Monday after his escape to South Korea, during which he was sacked on by four North Korean soldiers.
It's the same border area which was visited by US Secretary of Defense James Mattis less than a month ago.
The Unification Ministry said North Korean soldiers also defected across the JSA in 2007 and 1998, but military officials said no shooting occurred during those incidents.
"Our military maintains full readiness while strengthening the alert in preparation for the possibility of provocations by the North Korean army", the JCS said.
North Korea's military is preparing for winter drills, prompting South Korea to ensure its forces are combat-ready in case of any hostilities.
South Korean troops didn't fire at the North, he said.
The soldier suffered gunshot wounds to his shoulder and elbow, as well as a serious wound to his stomach. It is located inside the 4-kilometer-wide (2 1/2-mile-wide) Demilitarized Zone, which forms the de facto border between the Koreas since the Korean War.
North Korea has typically accused South Korea of enticing its citizens to defect, something the South denies.
The trip will come just a week after US President Donald Trump visited Beijing as part of a lengthy Asia tour, where he pressed for greater action to rein in North Korea, especially from China, with which North Korea does 90 percent of its trade.
President Xi's special envoy, Song Tao, will visit North Korea to inform its leadership about the outcome of the recent national congress of the ruling Communist Party of China (CPC), state-run Xinhua news agency said, without mentioning Trump's visit or the North Korea's nuclear programmes.
Tensions between the USA and North Korea have been sharply escalating in recent months with both sides indicating that they will not hesitate to engage in military action. While both sides of the DMZ are guarded by barbed wire fences, mines and tank traps, the JSA includes the truce village of Panmunjom which provides the site for rare talks and draws curious tourists.
The 1984 exchange of gunfire happened after North Korean soldiers crossed the border and fired, according to the U.N. Command. The attack prompted Washington to fly nuclear-capable B-52 bombers toward the DMZ in an attempt to intimidate North Korea.