Thomas Maresca

Special for USA TODAY

Shots were fired after a North Korean defector fled to the South on Thursday across the DMZ, the land border that divides the peninsula, South Korean military officials said.

The “low-ranking” soldier appeared at a checkpoint in a heavy fog, and walked across the military demarcation line a little bit after 8 a.m., according to an official from the Joint Chiefs of Staff, Yonhap News Agency reported.

After the defection, North Korean soldiers approached the border, apparently in search of the defector. In response, South Korean soldiers fired some 20 warning shots at around 9:30 a.m., the JCS official told reporters. More gunfire was heard around 40 minutes later, the official said, but no bullets were found to have crossed the border.

The crossing took place in the northeastern province of Gangwon, according to South Korean broadcaster KBS. Gangwon is where Pyeongchang, the city hosting the 2018 Winter Olympics in February, is located.

Four North Korean soldiers have defected this year.

Thursday’s incident comes just over a month after one of the most dramatic escapes in recent times.

On November 13, a North Korean soldier made a desperate dash across the Joint Security Area in the village of Panmunjom amidst a hail of gunfire by border guards from the communist nation. The 24-year-old defector was hit five times but survived after several rounds of surgery.

The Joint Security Area is the only part of the DMZ where soldiers from North and South can stand face-to-face, separated only by low concrete slabs that mark the military demarcation line. It is a popular tourist attraction and has hosted several U.S. presidents.

In a separate announcement, South Korea’s Unification Ministry said that two North Koreans defected to the South aboard a small wooden boat on Wednesday, Yonhap reported.