A massive landslide in mountainous northern India swept two packed passenger buses off a hillside Sunday into a deep gorge, killing 45 people, an official said.

The coaches had stopped for a tea break around midnight Saturday in Himachal Pradesh when tonnes of rock and mud swept away an entire stretch of a highway, roughly 200 kilometers (124 miles) from state capital Shimla.

Rescue teams reached the scene but struggled in the dark and steep terrain, with the army later joining the search for those still feared missing at the bottom of the ravine.

Forty-five bodies have been recovered from the accident site in the Himalayan state, said Sandeep Kadam, a senior official who has been at the scene since morning.

"After debris was cleared in the evening, we were expecting to find many of the bodies quickly," Kadam said late Sunday.

"The search operations will continue," he added.

Some houses and slum dwellings were also destroyed in the landslide, which followed days of heavy rain in the Himalayan region.

Landslides are common in India, especially during monsoon months when heavy rain loosens steep hillsides.