A hydropower project under construction in Laos failed Monday night, releasing a catastrophic torrent of water onto the rural villages below, sweeping away homes and people in a muddy tide.
Exactly how many people have been affected remains unclear.
More than 6,600 people are homeless, the Lao News Agency reported.
Bounyong Phommachak, a Red Cross official, said 24 bodies had been recovered and 96 people were officially listed as missing. It said the focus was on finding survivors and until they were all located the number of casualties would remain unclear. Photos and videos posted by state media show villagers, some just young children, perched on rooftops to escape the flood.
The Korean Federation for Environmental Movement said accelerating the dam's completion could have contributed to its collapse.
Also on Wednesday, Cambodia's Ministry of Water Resources told RFA's Khmer Service that the Lao dam collapse had caused the Sekong River's water level to rise by 11 meters (36 feet), causing flooding in two district in Stung Treng province and four districts in neighboring Ratanakkiri province.
South Korea, Singapore and neighbouring Thailand have offered to help in the rescue effort.
The Thai government said it would also send rescue experts to its northern neighbour.
Many areas of Laos have recently been hit by floods from heavy seasonal rains.
Provincial authorities issued a call for emergency aid, and residents in Paksong are streaming to the evacuation shelter bringing food, as doctors attend to those needing help.
South Korea's Yonhap News agency said SK E&C has dispatched its president to Laos and has set up an emergency team in Seoul.
The South Korean president said identifying who might be at fault can wait.
A senior Lao government official told Reuters by telephone from the capital, Vientiane, that dozens were feared dead after the failure of the dam - a subsidiary structure under construction as part of a hydroelectric project - on Monday.
Construction on the dam began in February 2013 and commercial operations were expected to begin in 2018 and was due to cost an estimated $1.02 billion. The second-biggest shareholder, SK Discovery Co Ltd (006120.KS), slid as much as 10 percent. SK Holdings Co., the biggest shareholder in SK E&C with a 44.48 percent stake, fell 3 percent.
Dam projects in Laos, mainly providing power to neighboring countries, have always been controversial with fears over environmental damage and the impact on communities who are often displaced to make way for the construction.
Dam projects in Laos, mainly providing power to neighbouring countries, have always been controversial with fears over environmental damage and the impact on local communities who are often displaced.