Eighteen persons, including eight women died on the spot while two succumbed to injuries, they said, adding the injured have been hospitalised in Rajgarh, Solan and Shimla.
This is the second major accident in the state in less than a month.
The private bus carrying around 35 passengers was on its way from Punradhar to Solan when the the mishap took place.
The government has ordered a magisterial inquiry into the accident and announced an immediate relief of Rs 10,000 to the next of kin of each victim.
39 people were killed on May 8 when an overloaded bus carrying 70 passengers had skidded off the road and plunged into the Beas river near Kullu town.