The United States urged North Korea on Sunday to halt any actions increasing the risk of conflict after the two Koreas exchanged fire across their heavily armed border earlier in the day.

The shootout happened as a group of about 10 North Korean soldiers approached the tense border, known as the Military Demarcation Line, and the South fired warning shots toward them after broadcasting messages urging them to turn back.

The North fired in return and the South fired back again in the 10-minute incident. There were no reports of casualties or property damage on the South Korean side, though no details were immediately known about the situation in the North.

The United States urged the North to stop any provocative actions.

"We are monitoring the situation in close coordination with our ROK allies," a State Department spokesperson said, referring to the South by the acronym of its official name. "We continue to urge North Korea to reduce tensions and cease any actions that could increase the risk of conflict."

Sunday's clash was the third exchange of fire between the two sides in less than two weeks. 

On Oct. 7, the sides exchanged gunfire after a North Korean patrol boat violated the western sea border. The second shootout came three days later on Oct. 10 after the North opened fire to try to shoot down large ballons carrying anti-Pyongyang leaflets.

The series of incidents came despite signs of a thaw in the long-stalled relations between the two sides in the wake of a surprise visit to the South by a group of three top North Korean officials earlier this month. (Yonhap)