At least ten people were killed in India’s state of Sikkim and 82 others, including 23 army personnel, were missing after heavy rainfall caused the glacial Lhonak lake to overflow, spurring catastrophic flooding in the region on Wednesday, officials said.

The northeastern state received 40.9 milimetre of rainfall between Tuesday and Wednesday morning, according to the India Meteorological Department (IMD) - almost five times its normal rate of 8.6 mm for this time of the year.

“So far, 10 bodies have been recovered from different locations. At least 82 more are missing and 22 people are injured, some of them seriously,” Sikkim Chief Secretary V B Pathak told Reuters.

A cloudburst - or an extreme amount of rain over a brief period of time - over Lhonak lake triggered torrential flooding in the valley located about 150 km (93 miles) north of Gangtok near the border with China.

“Intense rain has led to this catastrophic situation in Sikkim where the rain has triggered a glacial lake outburst flood and damaged a dam and caused loss of life and caused further damage to roads and infrastructure,” said Miriam Jackson, a senior cryosphere specialist at the Nepal-based International Centre for Integrated Mountain Development.

Heavy rainfall hampered the search for the Indian troops reported missing, with the capital city of Gangtok cut off by road, defence officials said.

“Twenty three personnel have been reported missing and some vehicles are reported submerged under the slush. Search operations are underway,” a defence ministry spokesperson said.

India’s weather department has warned of landslides and disruption to flights as heavy rain is predicted to continue over the next two days in some parts of Sikkim.

Jackson warned that such extreme events have become more frequent “as the climate continues to warm and takes us into unknown territory.”

The main highway linking Sikkim to West Bengal state had collapsed and Gangtok was totally cut off by road, according to army spokesperson Anjan Basumatary.

About 15,000 people living in the vicinity are likely to be affected and at least eight major bridges have been washed away along the banks of the Teesta river, officials said.

Media showed images of the river lashing through the hills and entering residential areas.

Some army bases and facilities along the valley were affected and rising water submerged vehicles following the release of water from a dam, a defence ministry spokesperson based in the neighbouring city of Guwahati said.

Intermittent rain and thunderstorms were hampering rescue operations in the area, an army official told Reuters, speaking on condition of anonymity.