Over a hundred people were missing after a huge chunk of glacier fell into a river in northern India on Sunday, setting off a torrent that inundated a hydro power complex and swept away roads and bridges, authorities said.
By the time nightfall had forced the suspension of the search, seven bodies had been found while officials said between 125 and 200 people remained unaccounted for.
Earlier in the day a glacier on the Nanda Devi national park broke up and fell into Dhauliganga river, setting off the high-speed floods that engulfed everything in their path.
Videos shared online by terrified residents showed the water tearing down cranes at a power plant and smashing up bridges and roads further downstream.
Dozens of workers in two power plants on the Rishiganga dam were missing and local inhabitants were swept away as they tended their cattle.
Uttarakhand state chief minister Trivendra Singh Rawat said that at least 125 were unaccounted for, but added that the number could increase.
State police chief Ashok Kuma earlier said there were 200 missing from the two power plants alone.
- 'Like an earthquake' -
About 20 workers were trapped inside one tunnel but 12 were rescued.
With the main road washed away, the tunnel was filled with sludge and rocks, and rescuers were forced to climb down a hillside on ropes to gain access to the entrance.
"There was a cloud of dust as the water went by. The ground shook like an earthquake," local inhabitant Om Agarwal told Indian TV.
Hundreds of troops and paramilitaries along with military helicopters and other aircraft have been sent to the region.
Authorities emptied two dams to stop the flood waters reaching the Ganges at the towns of Rishikesh and Haridwar, where authorities barred people from going near the banks of the river, officials said.
Villages on hillsides overlooking the sacred river were evacuated, but authorities later said the main flood danger had passed.
- 'Grim reminder' -
Prime Minister Narendra Modi said he was monitoring the relief operation.
"India stands with Uttarakhand and the nation prays for everyone's safety there," he said on Twitter.
Fourteen glaciers overlook the river from the Nanda Devi park, where fears over climate change and deforestation have mounted in recent years.
International experts say about a quarter of the ice on Himalayan glaciers have been lost over the past four decades because of increased temperatures.
"Avalanches are common phenomena in the catchment area," M.P.S. Bisht, director of the Uttarakhand Space Application Centre, told AFP. "Huge landslides also frequently occur."
The increased pace of development in the poor Himalayan regions has also heightened fears about fallout from deforestation and other environmental troubles.
Devastating monsoon floods and landslides in Uttarakhand in 2013 killed 6,000 people and led to calls for a review of projects in the state, particularly in isolated areas like those around the Rishi Ganga dam.
Former water resources minister Uma Bharti said she had called for a freeze on hydro-electric projects in "sensitive" Himalayan areas such as the Ganges and its tributaries when in government.
Vimlendhu Jha, founder of Swechha, an environmental group, said the disaster was a "grim reminder" of the effects of climate change and the "haphazard development of roads, railways and power plants in ecologically sensitive areas."
"Activists and locals have constantly opposed the massive river valley projects," he added.