North Korean troops fired shots Friday in the direction of a South Korean military unit across the border, prompting return fire, a South Korean military official said.
The clash took place along the demilitarized zone that separates the countries, in remote Gangwon province, northeast of Seoul. No injuries were immediately reported, Washington Post reports.
Two shots were fired first from the North Korean side at a military guard post near the border in Hwacheon, 118 km northeast of Seoul, South Korea's Yonhap said, quoting an official at the Joint Chiefs of Staff.
It remained unclear whether the North had opened fire on purpose or if it had been an accident, the report said. There were no initial reports of casualties on either side.
Shootings have occurred in the past at the heavily militarized inter-Korean border.
Relations between the two Koreas have deteriorated since March, when 46 sailors were killed in the sinking of a South Korean navy ship. Seoul blamed it on a North Korean torpedo, but Pyongyang denied any responsibility, according to Sify.