LUCKNOW, India — Part of an under-construction road tunnel in a mountainous north Indian state popular with tourists collapsed after a landslide Sunday, trapping more than 30 workers, officials said.

Rescue work is in progress and oxygen is being pumped through a pipe into the collapsed section of the tunnel to help workers breathe, said Manohar Tamta, an Uttarakhand state relief official.

“It will take some time to bring them out,” Tamta said.

The workers have sent out signals indicating that they are safe, the Press Trust of India news agency cited a state government official as saying.

“I am in touch with the officials on the spot and constantly monitoring the situation,” said the top state elected official, Pushkar Singh Dhami.

The collapsed portion of the tunnel is about 500 feet from the entrance, said police officer Arpan Yaduvanshi. Food is also being sent to the trapped workers, PTI quoted him as saying.

About 160 rescuers from federal and state disaster relief agencies are using drilling equipment and excavators to reach the workers.

Uttarakhand state is dotted with Hindu temples and sees a huge flow of pilgrims and tourists every year. It has expanded over the years with the massive construction of buildings and roadways. The Chardham all-weather road is a flagship federal government project connecting various Hindu pilgrimage sites.

In January, state authorities moved hundreds of people to temporary shelters after a temple collapsed and cracks appeared in over 600 houses because of the sinking of land in and around Joshimath town in the region