People gather near the debris of a bus after it crashed into a highway barrier and erupted in flames at Mehabubnagar in southern Andhra Pradesh state, India, on Wednesday.[Agencies]

A speeding bus exploded in a ball of flames after crashing into the central barrier of a southern Indian highway early on Wednesday, killing at least 45 passengers as they slept.

Only five people on the vehicle escaped the inferno, including the driver and the cleaner, who broke windows and fled before the fuel tank exploded, police said.

The bus, operated by Jabbar Travels, had been traveling overnight from Bangalore to Hyderabad and was passing another vehicle when it crashed into the roadside barrier in Mehabubnagar in southern Andhra Pradesh state.

"The total number of charred bodies found is 45, including that of a small child," said L. Sarman, a senior district administrative official.

"The driver was speeding at about 120 to 130 kilometers an hour. He was driving all night. It seems he may have fallen asleep at the wheel," Sarman said.

The bodies were charred beyond recognition and the bus was reduced to scrap in less than 10 minutes, witnesses said.

"The diesel tank burst and flames erupted. Before the passengers could realize what had happened, the blaze engulfed the entire bus," residents of the village were quoted as saying by local media.

There were 51 passengers on the bus. Most of the victims are believed to have been from Andhra Pradesh and going home for the Diwali lights festival early next month.

Managers of Volvo Buses in India said they are awaiting the results of a "full investigation" by authorities into the accident that involved one of its buses.

Sohanjeet Randhawa, head of marketing for Volvo Buses India, told The Hindu newspaper that the "tragic accident" involving the multiaxle vehicle, which is typically configured to carry up to 50 passengers, is being "studied" from all angles by the company.

"Our team has already arrived at the accident site, and we are still in the process of gathering all the relevant information," Randhawa said.

Asked if the results of the investigations could have a bearing on the design of the buses, Randhawa said a comprehensive investigation would look at all possible causes of the accident, including road design and other factors, according to the newspaper.

AFP-Xinhua-AP