At least 20 workers were killed after a portion of an under-construction tunnel collapsed following a gas explosion in the Indian Himalayas, officials said.

Incident occurred on Monday in Sikkim, where workers were constructing a tunnel for a state-run hydropower project; official says around 25-27 people trapped.

At least nine people have died and 15 others remained trapped after a tunnel collapsed at an under-construction hydroelectric project in India's remote northeast, officials said…