Reporting from Seoul — North Korea on Tuesday fired dozens of artillery rounds onto a populated South Korean island, killing two and injuring 19 others after Pyongyang claimed that Seoul was readying for "an invasion," officials said.
South Korean President Lee Myung-bak called an emergency session of his national security-related ministers in an underground bunker at the presidential residence late Tuesday to devise a response to the attack, which occurred near the disputed western border between North and South.
The Seoul government later called North Korea's artillery attack a "clear military provocation" and warned that the secretive regime would face "stern retaliation" should it launch further attacks.
Hong Sang-pyo, senior secretary for public affairs at the presidential office added that "recklessly shelling mere civilians can never be tolerated. North Korea will have to bear full responsibility" for the attack.
The South Korean military was placed on high alert, with fighter jets sent into the air, after officials confirmed that two South Korean marines were killed and 19 others -- including three civilians -- were injured.
South Korean soldiers returned fire, but it was not clear whether any North Koreans were killed or injured.
The South Korean military was conducting drills near Yeonpyeong island when the North opened fire about 2:30 p.m., officials said. Pyongyang had earlier sent messages to Seoul that it considered the exercises "preparation for an invasion," which South Korea denied, officials said.
Twenty minutes after the attack, the South Korean military returned fire and raised security alerts to their highest non-wartime levels. Just after 3 p.m., North Korea again began firing artillery from cliffside command posts less than 10 miles to the north.
Just before 4 p.m., South Korean military officials sent a message demanding a cease-fire, officials said.
Lee said he was trying to prevent the exchange of artillery fire between North and South Korea from escalating into a greater conflict, the Yonhap news agency reported.
In a statement, the South Korean Joint Chiefs of Staff said, "The North's firing comes as the South Korean forces conducted a routine drill in waters near the island."
A spokeswoman for Lee said the Seoul government was looking into the motive behind the sudden attacks.
