South Korean officials said their troops exchanged fire with North Korea Sunday morning along the tense land border dividing the two countries.

North Korean troops fired several bullets at a South Korean guard post inside the heavily fortified border between the countries, the Joint Chiefs of Staff in Seoul said in a text to NBC News. No casualties or damages to equipment were reported.

South Korean military personnel fired two rounds in response after issuing a warning broadcast.

“We are in the process of taking measures to ensure that no additional situation occurs,” the joint chiefs of staff said. They added that they were communicating with North Korea through a military line, while staying prepared for further fire.

The Koreas are split along the Demilitarized Zone that was originally created as a buffer. But despite what its name suggests, the DMZ is the world’s most heavily fortified border.

U.S. Secretary of State Mike Pompeo on Sunday confirmed the exchange of fire on ABC’s “This Week with George Stephanopoulos.”

“We think those were accidental. The South Koreans did return fire,” Pompeo said. “So far as we can tell, there was no loss of life on either side.”

Sunday’s incident came one day after North Korean leader Kim Jong Un reportedly appeared in public for the first time in nearly three weeks, dispelling rumors that he was dead or severely ill.

When asked about the photos of Kim that were recently shared, Pompeo said his absence from the public was “not unprecedented.”

“So there’s not much I can share with you, other than we’ve seen the same images from yesterday that the world saw,” Pomepo said. “It looks like Chairman Kim is alive and well.”

Doha Madani contributed.