The accident occurred around 100 kilometres (62 miles) from the hill resort of Shimla in Himachal Pradesh state, said police superintendent Soumiya Sambasivan.
"28 people have died and seven are injured. All the bodies have been identified," she said.
The bus was taking around 40 people from Kinnaur district towards Solan when it rolled roughly 200 metres down a gorge to the banks of a river river.
Images from the scene showed emergency workers conducting a rescue operation with the help of local volunteers.
Last week, 16 pilgrims died in a bus crash in neighbouring Jammu and Kashmir state, while in April 44 people were killed in Himachal Pradesh in a similar accident.
India has some of the world's highest traffic fatalities with more than 150,000 deaths annually due to poor roads, badly maintained vehicles and reckless driving.
Information Source: Pulse News