At least two South Korean soldiers are dead after North Korea began an artillery assault on a disputed island controlled by the South, around 2:30 p.m. local time on Tuesday. The exchange is among the fiercest clashes since the Korean War effectively ended in 1953. The attack came after South Korea refused to halt military exercises in the area, though North Korean state media reports that the South fired first. The South responded to the onslaught with artillery of its own, and residents of the island, which has both civilians and military installations, escaped to the mainland or went into shelters. The North has reportedly dropped more than 200 shells on the island, leaving at least 70 homes ablaze. The clash comes after weeks of tensions following Pyongyang’s announcement of a new uranium enrichment facility, and just a month after North Korean leader Kim Jong Il announced his youngest son, Kim Jong Un, to be his heir. The island, Yeonpyeong, was the site of two previous deadly clashes in recent years, in 2002 and in 1999. Officials from Beijing to Washington were on high alert as tensions mounted between Seoul and Pyongyang. The White House “strongly condemns the attack” and “is firmly committed to the defense” of South Korea, according to a statement from Robert Gibbs that called for North Korea to “halt its belligerent action.” In addition to the two fatalities, 17 soldiers and three civilians were wounded in the attack.