The tunnel, which was being constructed on a national highway that is part of a Hindu pilgrimage route, collapsed early Sunday morning.

“Rescue workers are preparing an escape passage by drilling the debris,” local police superintendent Arpan Yaduvanshi told Reuters on phone.

“Food and water was supplied to the labourers and we are hopeful that the rescue operation will be completed soon. Everyone inside, about 40 labourers, is fit,” the police officer said.

Uttarakhand in north India is vulnerable to landslides, earthquake and floods.

The Char Dham pilgrimage project is one of the most ambitious projects of Prime Minister Narendra Modi’s government. It aims to connect four important Hindu pilgrimage sites of North India through 889 kilometres (552 miles) of two-lane road being constructed at a cost of $1.5 billion.

(Reporting by Saurabh Sharma; Writing by Kanjyik Ghosh;Editing by Shri Navaratnam)