Media reports in India say a flash flood caused by heavy rains in the mountains of the northeast has killed at least 14 people and left more than 100 missing.

India's disaster management authorities said torrential rain in the state of Sikkim since Tuesday caused a lake to overflow, triggering a flash flood along a river.

Media reports say military officials are among the missing.

Footage taken of the affected area shows muddy currents, inundated buildings and collapsed roads. A resident is seen saying the situation is serious, and that the flood swept away his house and all of his belongings. He says the roads have been damaged, blocking traffic.

Military personnel and police are conducting search and rescue operations.

Prime Minister Narendra Modi said in a social media post that he will send as much aid as possible to the flood-hit area to overcome the difficulties.

Weather officials in the region are warning of more rain and floods, and advising people to stay on alert.