Seoul, May 3 (IANS): Several gunshots from North Korea hit a South Korean guard post inside the Demilitarized Zone (DMZ) on Sunday, prompting the South to retaliate, but the North's firings do not appear to have been intentional, an official said here.

South Korean soldiers on guard duty at the unit in the central border town of Cheorwon heard gunshots at 7.41 a.m. and found four bullet marks on a wall of the guard post, Yonhap News Agency quoted the Joint Chiefs of Staff (JCS) as saying.

The military then fired a total of 20 shots in response and issued broadcast warnings, it added.

No casualties or damage to South Korean facilities were reported.

It was not known if North Korea sustained any damage.

"We also sent a notice to the North Korean side via the inter-Korean communication line at around 9.35 a.m., and called for its explanation," a JCS officer said.

The South Korean military was closely looking into the incident to learn more details by analyzing pieces of evidence, including shells found at the scene, as well as the North's motivations for the firing.

It does not appear to be an intentional provocation, according to the officer.

"It was quite foggy and the North Korean soldiers usually rotate shifts around that time," Yonhap News Agency quoted the JCS officer as saying, adding that no unusual movements by the North's military have been detected.

The South Korean authorities made it clear that the incident was in violation of the bilateral military accord of the Comprehensive Military Agreement signed in September 2018, and urged the North to fully abide by the agreement.

Under the accord, the two Koreas set up land, maritime and ground buffer zones and agreed to halt all hostile acts against each other, aimed at reducing tensions and building trust.

It is the first reported exchange of gunfire between the two Koreas along the border since 2017, when the North fired bullets at one of its soldiers who was fleeing to the South.

The incident came amid stalled inter-Korean relations and one day after the North ended mounting rumours about leader Kim Jong-un's health and whereabouts by reporting his first public appearance in nearly three weeks.