NEW DELHI — A Himalayan glacier broke and caused sudden, massive flooding in the northern Indian state of Uttarakhand on Sunday, smashing two dam projects and forcing the authorities to scramble to evacuate villages and try to save more than 100 lives.
Trivendra Singh Rawat, the chief minister of Uttarakhand, said that seven bodies had been recovered and that about 125 people, many of them workers at the two hydroelectric dam projects that were largely swept away, were unaccounted for.
“An avalanche came and completely broke the Rishiganga power project, and almost all the workers there are missing,” said Ashok Kumar, the chief of police in Uttarakhand. “By the time the water came downstream, we had alerted people.”
The scenes were reminiscent of floods in Uttarakhand in 2013, when heavy rain over several days led to landslides that killed thousands of people and washed away entire villages.
But the latest disaster also raised fears of what is to come. Scientists, who said the breaking of a glacier in the middle of the winter appeared to be a result of climate change, have warned that rising temperatures are melting the Himalayan glaciers at an alarming pace. The glaciers, which supply water to tens of millions of people, could be mostly gone by the end of the century, a recent study found.
The district of Chamoli in Uttarakhand appeared to have been hit hardest by the surging Dhauliganga River. Amit Shah, India’s home minister, said teams from the country’s disaster response force had been airlifted in. Hundreds of soldiers and members of the Indo-Tibetan Border Police also descended on the scene, other officials said.
Videos on social media showed violent surges of water heading down mountain gorges, washing away bridges and what looked like hydroelectric structures of one of the dams.
Officials said 35 people had been working on the Rishiganga power project closer to the glacier that was swept away, and 176 other people on a second project about three miles downstream.
Ratan Singh Rana, 55, from the village of Raini near the Rishiganga project, said the water rushed down the mountain around 10:30 a.m.
“I was sitting on the floor of my house,” he said. “I saw black liquid flowing from the Nanda Devi mountainside — down with a lot of noise — as if a volcano had erupted.”
“It was only 20-25 meters away from us,” he added. “We ran uphill about 250 meters and kept on crying and shouting, ‘Bhago, bhago! Bachao, bachao!’” he said, using the Hindi words for “run” and “save us!”
Mr. Rana said the muddy water swept big boulders and ice downstream. His daughter and granddaughter were trapped in the house with mud rubble closing off the main entrance. They managed to rescue them from the back of the house.
“We thought that the whole world would drown in this,” he said. “I was thinking that today is the end, that we would leave this world today.”
By late Sunday afternoon, it appeared that the worst of the damage from the flooding was over.
Mr. Rawat, the chief minister, visited Chamoli and posted a video on Twitter that indicated the flow of water had slowed. He expressed hope that some of the missing people could be rescued. Local news media reports said 16 people trapped in a tunnel had been rescued so far.
“Our special focus is on rescuing the workers trapped in the tunnels,” he said.
The disaster led critics to point fingers at the government for constructing a dam so close to the glaciers at a time when the area is so vulnerable to climate change.
Uma Bharti, a former minister for water resources and river development in the government of Prime Minister Narendra Modi, said she had warned against placing a hydroelectric project on the river so close to the Himalayas.
“This incident, which happened in the Himalayas at Rishiganga, is a matter of both concern and warning,” Ms. Bharti said on Twitter. She said she had warned that the Himalayas are “a very sensitive area, and that is why on Ganges and its tributaries these projects should not be constructed.”
Anil Joshi, an environmentalist who studies the Himalayan region, said the dam that was swept away was built just a few miles from the Nanda Devi glacier, on India’s second highest mountain.
“At this time, a glacier avalanche indicates climate change,” Mr. Joshi said, referring to how the episode has occurred during the winter cold. “Temperature variation caused the detachment of glaciers, and that damaged the hydro dam at Rishiganga.”
Mr. Joshi said he struggled to understand why the government had built the dam so close to the glacier. “Now this water is flowing with cyclonic speed.” he said.