The bus carrying about 35 passengers was on its way from Punradhar to Solan when the the mishap took place.
The bus started from Punradhar, around 7 AM and the accident took place just five km from the starting point, Sirmaur SP, Sumedha Dwivedi, who was on way to the spot, said over phone.
Eight bodies have been recovered and death toll may rise as some people were critically injured while some bodies were feared trapped in the wreckages of the bus.