The North Korean military fired at a South Korean naval patrol boat Thursday. The two sides exchanged fire but no one suffered damage.

An official at the Joint Chiefs of Staff told reporters that the North fired two shells at the South Korean vessel at around 6 p.m. in the Yellow Sea. 

The shells were dropped about 150 meters off the South Korean ship, a guided missile patrol boat which was patrolling waters about 14 kilometers southwest of Yeonpyeong Island.

After the initial attack, the South Korean ship immediately returned five rounds of fire.

The South Korean military said that it is closely monitoring the North to deal with any additional provocations.