A glacier break in Joshimath in Uttarakhand’s Chamoli district led to an avalanche and massive flooding on Sunday in the upper reaches of the ecologically fragile Himalayas. Uttarakhand Chief Secretary Om Prakash told ANI that 100 to 150 people may have died due to the flash floods.

The flooding took place along Dhauliganga and Alaknanda rivers. A witness said he saw a wall of dust, rock and water as an avalanche roared down a river valley. “It came very fast, there was no time to alert anyone,” Sanjay Singh Rana, who lives on the upper reaches of Raini village, told Reuters. “I felt that even we would be swept away.”

The Rishiganga Power Project has been damaged and Uttarakhand Director General of Police Ashok Kumar said the power project at Tapovan-Reni has been swept away completely.

“The situation is under control now,” Kumar said. “There is a dam at Srinagar and it has contained the flow. The power project has taken the damage.”

The state police chief said people who were working in and around the power project are among the ones missing.

Uttarakhand Chief Minister Trivendra Singh Rawat said teams from the police, the Army and the Indo-Tibetan Border Police, as well as from the national and state disaster response forces, had been deployed and “are doing their best to save the lives of the workers at sites affected by the disaster”.

ITBP spokesperson Vivek Kumar Pandey told PTI that three bodies have been recovered so far. The spokesperson added that due to the collapse of at least three bridges in Reni village, including one of the Border Roads Organisation, connectivity with some of their border posts has been “totally restricted”.

Prime Minister Narendra Modi, who is on visit to Assam and West Bengal, said that he was constantly monitoring the situation. “India stands with Uttarakhand and the nation prays for everyone’s safety there,” he tweeted. “Have been continuously speaking to senior authorities and getting updates on NDRF deployment, rescue work and relief operations.”

Union Home Minister Amit Shah also said that he has spoken to the chief minister. “All the concerned officers are working on a war footing,” he tweeted. “NDRF teams have left for rescue operations. Every possible help will be provided to Devbhoomi [Uttarakhand].”

Finance Minister Nirmala Sitharaman assured that all necessary assistance will be extended to the Uttarakhand government. “There shall not be any hesitation on that,” she added.

The Uttarakhand chief minister, meanwhile, tweeted out helpline numbers. “If you are stranded in the affected area, if you need any kind of help, please contact Disaster Operations Center number 1070 or 9557444486,” he said. “Please do not circulate old videos and rumours at this time.”

An alert has been issued for all downstream districts, NDTV reported. The residents of Rudraprayag, Rishikesh and Haridwar have been advised not to go to river banks.