Four North Korean soldiers fired 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 since 1984, the South's military said Tuesday.
A U.N. Command helicopter later transported him to the Ajou medical center, according to South Korean officials.
The JSA is jointly overseen by the American-led U.N. Command and by North Korea, with South Korean and North Korean border guards facing each other only meters (feet) apart.
Monday's shooting was the first at the Joint Security Area since North Korean and U.N. Command soldiers traded gunfire when a Soviet citizen defected by sprinting to the South Korean sector of the JSA in 1984.
A North Korean soldier defected there in 1998 and another in 2007 but neither of those events involved gunfire between the rivals, according to South Korea's military.