
The bus, carrying more than 50 passengers, was travelling from Bangalore city to Hyderabad, Andhra Pradesh's capital, when the incident happened early on Wednesday.
Seven people, including the driver, managed to escape the blaze.
Police say a collision with a culvert ignited the fuel tank of the vehicle.
The incident happened at Kothakota in Mahbubnagar district, 140km (86 miles) from Hyderabad, when the air-conditioned Volvo luxury bus...