Twenty-three Indian troops were reported missing on Wednesday after a flash flood caused by a cloudburst in the northeastern state of Sikkim, a defence spokesperson said.

The rain lashed a valley about 150 km (93 miles) north of Gangtok, the state capital, located along the border with China.

“Some army establishments along the valley have been affected and efforts are on to confirm details,” said the spokesperson based in the city of Guwahati.

Rising water submerged some vehicles following the release of water from a dam, the spokesperson added.

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

Reports from India media quoted officials to say that families of missing soldies had been informed and a ‘massive’ search operation was underway.

The reports added that all except 23 Indian soldiers in the region were safe but they were unable to get in touch with their families as the rains had caused disruptions to communication networks.