At least 16 children aged between five and 15 have been burned to death in a school bus fire in eastern Pakistan.
At least seven more children were taken to hospital after the incident on the outskirts of the city of Gujrat.
Initial reports said the bus's gas cylinder had exploded, but a local police chief has told the AFP news agency it was later found intact.
He says a teacher also died in the fire. Another police officer says the driver survived and fled.
The officer, Dar Ali Khattak, says the fire was apparently caused by a spark when the driver of the dual-fuel bus switched from gas to petrol.
Compressed natural gas is used in millions of vehicles in Pakistan as a cheaper alternative to diesel and petrol. Numerous previous vehicle explosions have been blamed on substandard cylinders used to contain it.