A lorry carrying fuel has burst into flames near the Pakistani city of Ahmedpur East, killing at least 150 people, local officials say.
Villagers had gathered, reportedly to collect fuel leaking from the crashed tanker, when it caught fire. Dozens are being treated in hospital.
It appears the tanker blew a tyre while rounding a sharp bend in the road.
The fire was sparked by a passer-by lighting a cigarette, a rescue services spokesman told the BBC.
“The incident, which was a minor [one], turned into a major blast,” Jam Sajjad said.
Prime Minister Nawaz Sharif is cutting short a visit to London in response to the incident, the Pakistani government news agency, APP, reported.
Army helicopters were dispatched to ferry casualties to hospitals, army spokesman Maj Gen Asif Ghafoor said in a tweet. There are fears that the death toll could rise further.
Some of the victims may only be identified by DNA sampling, as the bodies were so badly burned in the incident, reports say.
Police sources told APP that the tanker had been transporting 25,000 litres (5,500 gallons) of fuel from Karachi to Lahore.