Indian emergency workers were on Sunday trying to reach dozens of workers trapped after the collapse of an under-construction tunnel that was hit by a landslide in the Himalayan state of Uttarakhand.
The incident occurred when a group of workers was moving out and replacement workers were going in.
Police said up to 40 could have been trapped after a part of the Silkyara tunnel on a national motorway in the town of Uttarkashi collapsed about 6am local time.
Disaster response forces, police and local administration launched a rescue operation, in which oxygen pipes were inserted through the debris to help the trapped workers to breathe.
No deaths have been reported.
A message was sent to the trapped workers through a tube that is pumping oxygen into the blocked portion of the tunnel, assuring them "all efforts are being made for your safety", AFP cited Durgesh Rathodi, a state disaster response official, as saying.
“The incident took place early this morning," said Arpan Yaduvanshi, the Uttarkashi police chief. "We have sent all the necessary equipment and machinery required for the rescue work.
“A part of the tunnel has broken about 200 metres ahead of the starting point. At least 36 people are trapped and efforts are being made to rescue them safely."
The 4.5-kilometre (2.7-mile) tunnel is being constructed between Silkyara and Dandalgaon to connect two of the holiest Hindu shrines of
Uttarkashi and Yamnotri.
Photographs released by the government rescue teams showed huge piles of concrete blocking the wide tunnel, with twisted metal bars on its broken roof poking down in front of the rubble.
A local police officer told the Press Trust of India news agency they were "very optimistic" the men would be rescued safely, but added it was "difficult to say how long it will take".
The tunnel is a part of Prime Minister Narendra Modi’s ambitious Char Dham all-weather road project, to improve connectivity to four Hindu pilgrimage sites in the state.
Nestled in the lap of the Himalayas, Uttarakhand is known for its natural beauty and houses dozens of major Hindu temples, receiving tourists all year round.
But the ecologically sensitive region has been facing the brunt of climate change and rampant construction.
The state has been hit by disasters, including deadly floods in 2013 that devastated Kedarnath, one of the holiest Hindu shrines, killing more than 5,700 people. A glacial lake burst in 2021, triggering a flash flood at a hydropower project construction site that killed at least 200.
At least 50 people were killed this summer after unprecedented heavy rain caused flash flooding and landslides.