SEOUL -- Naval ships of the two Koreas traded warning fires in the western sea boundary after a patrol ship of the Democratic People's Republic of Korea (DPRK) violated the disputed maritime border, Yonhap News Agency and YTN reported Tuesday.

One DPRK patrol ship sailed around 1 km south of the Northern Limit Line (NLL) at about 9:50 a.m., violating the disputed western sea border, South Korea's Joint Chiefs of Staff (JCS) was quoted as saying.

South Korean patrol ships issued warning communications to make the DPRK ship return to its territorial waters, but the DPRK ship stayed there until the South Korean ships issued warning fires with machine gun.

The DPRK ship fired back at the South Korean ships, which in response fired machine guns against the DPRK ship.

After exchanging machine gun fires, the DPRK ship returned to the north.

No warships of both sides fired aimed shots against each other. No casualties have been reported from the South Korean ships.