North and South Korea have exchanged gunfire in the Demilitarised Zone which divides the two countries.
Seoul’s military said shots from the North hit a guard post in the central border town of Cheorwon. It said it returned fire and delivered a warning announcement.
Such incidents across the world’s most heavily fortified border are rare.
South Korea’s military says the shots were not likely to have been intentional.
US Secretary of State Mike Pompeo also told US media the shots from the North were believed to be “accidental”.
No injuries were reported in the incident. Military officials in the South say there was no sign of unusual troop movements.
The last time the North opened fire on the South happened in 2017 when a North Korean soldier made a dash across the military demarcation line to defect.