At least four workers have died after an avalanche swept away a large construction crew working on a highway near India’s mountainous border with Tibet, Indian army said Saturday.

The incident took place near the Mana Pass in northern Uttarakhand state on Friday, and 55 construction workers were initially trapped under snow. Rescuers pulled out 50 workers, of whom four later died, the Indian army said in a statement.

It said the search for the five remaining missing workers was continuing, with multiple teams of rescuers and military helicopters scanning the incident site. The statement did not specify the number of injured but said they were “being prioritized for evacuation.”

Chandrashekhar Vashistha, a senior administrative official, said some of the workers had sustained serious injures and were hospitalized.

Many of the trapped workers were migrant laborers who were working on a highway widening and blacktopping project along a 50-kilometer (31-mile) stretch from Mana, the last village on Indian side, to the Mana Pass bordering Tibet.

“Rescue operations were slow due to heavy snowfall, and the area remained inaccessible,” said Kamlesh Kamal, a spokesperson for the Indo-Tibetan Border Police. He said the rescuers had to work through several feet of snow, snowstorms and poor visibility.

Avalanches and landslides are common in the upper reaches of the Himalayas — especially during the winter season.

Scientists have warned, however, that climate change spurred by human burning of fossil fuels is making extreme weather events more severe and less predictable, as winter snow and ice melts faster and storm systems are super-charged over the Earth’s warmer oceans.

In 2021, almost 100 people died in Uttarakhand after a huge glacier chunk fell into a river, triggering flash floods. Monsoon floods and landslides in 2013 killed 6,000 people and led to calls for a review of development projects in the state.