The driver lost control as he hit a speed bump on a road leading from the popular Anjaneya Swamy temple in Telangana state, about 190 kilometers (118 miles) from Hyderabad, the state capital, Transport Minister P Maneder Reddy said.
The overcrowded bus pitched into a gorge.
Crowds often throng the temple on Tuesdays. The temple is dedicated to the Hindu god Hanuman, and Tuesdays are seen as auspicious for offering prayers to him, Al Jazeera
Passersby rushed to help after the bus crashed, mangling the front of the vehicle. Volunteers crawled into the bus through broken windows, carrying the dead and injured though thick grass and up the hill to the road. The injured were taken to area hospitals.
An investigation has been ordered into the cause of the accident, the official, who uses only one name, said.
TV network NDTV quoted witnesses as saying the driver was speeding and lost control of the vehicle.
Accidents on Indian roads claim the lives of more than 150,000 people each year, with most accidents blamed on poor roads, badly maintained vehicles and reckless driving.
On July 28, a bus carrying university workers plunged off a mountain road into a valley in western India, killing 33 people.
That vehicle was taking staff from the Dapoli Agriculture University for a picnic at a popular hill station in the western state of Maharashtra.
The same month, 48 people were killed and many others badly injured in the north of the country when an overcrowded bus hurtled into a gorge in the Himalayan foothills.
