23 Indian soldiers are missing and presumed dead after a catastrophic flash flood caused by heavy rain ripped through a valley in hilly northeastern Sikkim.

"Due to sudden cloud burst over Lhonak Lake in North Sikkim, a flash flood occurred in the Teesta River... 23 personnel have been reported missing and some vehicles are reported submerged under the slush," the army stated in a statement.

PHOTO | COURTESY flooding

Lhonak Lake is located near India's border with Nepal, at the base of a glacier amid the snowy peaks that encircle Kangchenjunga, the world's third-highest mountain.

According to the army, the river was already more than 4.5 meters higher than typical due to water discharged upstream from the Chungthang dam.

PHOTO | COURTESY 23 soldiers killed in a flash flood

Flash floods are widespread during the monsoon season, which begins in June and typically ends in September across the Indian subcontinent. The heaviest monsoon rains are usually over by October.

According to experts, climate change is increasing the frequency and intensity of these events.