The army and the National Disaster Response Force (NDRF) have reached the spot and are carrying out rescue operation.
So far, 10 bodies have been recovered from the debris. "Pained by the loss of lives due to landslide related accidents in HP's Mandi district".
The landslide happened at Kotrupi, 220 kilometres from Shimla. Rescue operation has been under way since 2am, he said, adding, one bus was going to Chamba while another to Katra from Manali when the incident took place.
At least a dozen small vehicles are also trapped.
Hundreds have died across India in torrential rain, floods and landslides since the onset of the wet season in April.
As per reports, National Highway 21 from Mandi to Aut has also been closed for traffic due to landslide threats.
Rescue operations at accident site.
The landslide swept away the road and the buses for nearly 800 metres down into a gorge and there was no trace of one of the buses which was completely buried under the debris so far.
The Mandi district administration received the information about the incidents around 12.35am and the rescue operation team was rushed to the spot.
One of the buses was on its way to Chamba from Manali, while the other one was on its way to Katra in Jammu from Manali. "We are not sure how many people were in this bus", he told AFP.