Race to rescue dozens of workers trapped by tunnel collapse in Uttarakhand, India

Rescuers will need to clear as much as 150 metres of caved-in tunnel to reach stranded workers

Workers became trapped after an under-construction tunnel collapses in Uttarakhand, India (Screengrab/ANI)

Rescue operations are underway to save nearly 36 workers feared trapped inside an under-construction tunnel that collapsed on Sunday in India's Himalayan state of Uttarakhand.

A 150-metre portion of the structure collapsed around 4am (local time) on Sunday, trapping a team of construction workers.

The 4km-long tunnel in Uttarkashi district is being built to connect the Silkyara and Dandalgaon regions in an effort to reduce the journey from Uttarkashi to Yamunotri Dham, a Hindu religious shrine, by about 26km.

The National Disaster Relief Force (NDRF), State Disaster Relief Force (SDRF) and the local police have been pressed into action to rescue the workers.

A narrow opening has been made to insert an oxygen pipe while the rescue workers continue their effort to clear nearly 200 metres of slab to open the tunnel.

Devendra Patwal, the district’s disaster management officer, said the workers were not crammed inside the tunnel and had a buffer space of around 400 metres to “walk and breathe”.

“They have enough oxygen to easily survive for over 8-10 hours, and that should give us enough time to rescue them,” he told The Indian Express.

Uttarakhand chief minister Pushkar Singh Dhami said he had been in contact with officials since he was first informed of the incident on Sunday morning.

"NDRF and SDRF are at the spot. We pray to god for the safe return of everybody," he told news agency ANI.

Vertical drilling machines were reportedly being arranged to cut through the debris, the authorities said, but some officials said it could still take up to three days to evacuate the workers.

Falling rubble posed a significant challenge for rescuers trying to remove the obstruction. Photographs released from the accident site showed huge piles of concrete blocking the tunnel as metal bars poked down in front of the rubble.

Uttarkashi’s police superintendent Arpan Yaduvanshi told the Press Trust of India that rescue operations were “under way on a war footing”. “Around 36 workers are trapped inside, as per record[s],” he said. “We will rescue all of them safely.”

He said there had been “no casualty reported so far”.

Five ambulances have been brought to the accident spot for the trapped workers.

The construction workers were reportedly from the eastern states of Bihar and Jharkhand.