The victims died on the spot following the explosion in south-central province of Khanh Hoa.

President Barack Obama on Tuesday pledged help to clear away the 80 million unexploded bombs the U.S. dropped on Laos a generation ago — more than 10 for every one of the country's 7 million people.

Almost half a century later, scars from the U.S. Air Force's bombings are still visible in Laos' Xieng Khouang Province, the area in the impoverished country most heavily bombed during the Vietnam War.