Photo by BBC from the scene

At least 14 people are dead and 150 missing after a piece of a Himalayan glacier fell into a river and triggered a huge flood in northern India.

The floodwaters burst open a dam and a deluge of water poured through a valley in the state of Uttarakhand.

Uttarakhand police said an avalanche struck at about 11:00 local time (05:30 GMT) on Sunday, destroying a dam known as the Rishiganga Hydroelectric Project.

Police said the impact catapulted water along the Dhauli Ganga river, damaging another power project downstream in the Tapovan area.

Senior police officials told media that a bridge in the Tapovan area that connected 13 villages was washed away in the avalanche.

Most of the missing are believed to be workers from two hydro power plants in the area.

Hundreds of troops, paramilitaries and military helicopters have been sent to the region to help with rescue efforts.

Experts are investigating the incident though it is not yet clear what might have caused the glacial burst. Officials say 25 people have been rescued so far.

In a tweet on Sunday, Indian Prime Minister Narendra Modi said he was keeping a close watch on the situation in Uttarakhand.

“Have been continuously speaking to authorities and getting updates on… deployment, rescue work and relief operations,” he said in a tweet.

Leaders from across the world have also sent their condolences to families of the victims.

“My thoughts are with the people of India and rescue workers in Uttarakhand as they respond to devastating flooding from the glacier collapse,” said UK Prime Minister Boris Johnson in a tweet.

“The UK stands in solidarity with India and is ready to offer any support needed.”

BBC