Emergency workers are searching for as many as 200 people still missing after a piece of a Himalayan glacier fell into a river.
This triggered a huge flood in northern India, killing 18.
The floodwaters burst open a dam and a deluge of water poured through a valley in the state of Uttarakhand on Sunday.
Most of the missing are believed to be workers from two hydropower plants.
The rescue effort is focused on several sites, including a tunnel more than 200 metres (656ft) long.
More than 30 people were apparently trapped inside when the torrent of icy water swept down the valley, carrying rocks and earth as it gathered speed.
There has been no contact with them since. The rescue teams hoped to clear the tunnel by nightfall.
Hundreds of troops, paramilitaries and military helicopters have been sent to the region to help with rescue efforts.
An investigation is continuing into what caused the glacial burst.
