North Korea fired artillery into areas in the Yellow Sea near South Korea's Yeonpyeong Island on Tuesday afternoon, with some of the artillery shells actually landing directly on the island.

The Joint Chiefs of Staff (JCS) in Seoul says the North fired dozens of artillery shells from its coastal base toward Yeonpyeong at around 2:34 p.m. The South Korean military responded by firing shots of its own toward the North using its K-9 self-propelled guns.

A JCS official says that the military is operating in crisis management mode and is on full alert to prepare against further provocations.

Two South Korean Marines died during the attack and 13 other soldiers were injured, three of them seriously. Two South Korean civilians were also reportedly injured.

The JCS has issued a top military alert for five islands in the area.

Military sources say 200 shells landed on Yeonpyeong Island, destroying several houses and starting a fire in the mountains.

Residents of Yeonpyeong are being evacuated by the military, and President Lee Myung-bak has convened a meeting of the National Security Committee to discuss the situation.

South Korea was conducting a maritime firing drill in waters near Yeonpyeong Island when the North fired the artillery shells. The South's exercise started Monday and is scheduled to last until next Tuesday. A JCS official says it is a routine military exercise during which South Korean troops only fire southward.