South Korea’s semi-official Yonhap news agency reported Tuesday that North and South Korean naval forces have exchanged fire.

Citing an unnamed South Korean defense official, Yonhap reported that the two Koreas clashed off their west coast, where previous skirmishes in 1999 and 2002 turned deadly.

The official said, “No South Korean casualties were immediately reported.”

A North Korean patrol ship crossed into South Korean waters, prompting the South’s navy to fire warning shots, he added. The North Koreans then fired back.

The two Koreas dispute the exact location of the sea border between their countries.

A series of incursions by navy ships from North Korea into South Korean waters was followed by a clash in 2002. In that incident, at least four South Korean sailors died and nine others were wounded.

Several border violations by North Korean ships in June 1999 sparked the first naval clash between the two Koreas since the 1950-53 Korean War.

(article and photo source: CNN)