BANGKOK — The wall of water, unleashed by a dam failure, roared through a half-dozen rural villages in Laos, sweeping away hundreds of people in its torrents.

On Tuesday, many of those people were nowhere to be found, and while only several people have been confirmed killed, Laotian officials feared the worst.

The dam, which was still under construction, gave way on Monday, forcing nearly 7,000 people to flee their homes.

Photos and videos from the scene showed murky, brown water covering a vast area, with residents seeking refuge on rooftops that barely remained dry. Others could be seen walking knee deep in water out of the flooded area or escaping on boats with only a few possessions in hand.