A speeding bus exploded in a ball of flames after crashing into the central reservation on a southern Indian highway early Wednesday, killing 44 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 number of dead, which includes children, is 44," local police spokesman Venkateshwarlu, who uses only one name, told AFP.
Fatalities were high even by deadly Indian standards where bus crashes, particularly on the treacherous roads of the northern Himalayas, are common.
Venkateshwarlu said the driver and cleaner had tried to flee the scene of the accident, which occurred around 5:00 am (2330 GMT Tuesday) between Bangalore and Hyderabad.
"The police caught them and they are now in our custody for questioning," he said.
Relatives of the victims screamed and broke down in tears outside the office of the bus operator in Hyderabad, 140 kilometres (85 miles) from the crash site.
Police arrived later to question the owners of Jabbar Travels, which offer buses to cities across the south of India.
Many of the victims were charred beyond recognition. Television pictures showed flames leaping out of the vehicle, which was completely gutted by the time firefighters arrived.
The survivors were being treated in a nearby hospital in Wanaparthy, Venkateshwarlu said.
The Times of India reported that at least five of the victims were software engineers who were travelling home to celebrate Diwali, the Hindu festival this Sunday.
Both Hyderabad and Bangalore are centres of India's booming IT industry, while Diwali is one of India's biggest festivals which sees tens of millions of migrants head back to their families.
"The main reason why the mishap occurred was because the bus was speeding and it hit against a road divider," district official Girija Shankar told the newspaper.
Around 140,000 people died in road accidents in India in 2012, according to the government's National Crime Records Bureau, which works out at 16 an hour.
Bad roads, speeding vehicles and poor driving are among the contributing factors.
Commercial drivers are largely unregulated, meaning many work long hours overnight which raises the danger of them falling asleep at the wheel, campaigners say.
In May at least 33 people died when an overcrowded bus skidded off a road into a fast-flowing river in the northern state of Himachal Pradesh.
At least 30 were killed earlier this month in the northeastern state of Assam when a heavy goods truck careered onto the wrong side of the road and smashed head-on into two packed vehicles.
The World Health Organisation's global status report on road safety 2013 found that eight percent of India's road user deaths were bus drivers or passengers while 32 percent were riders of motorbikes or three-wheelers.