The van, carrying 20 to 25 children, caught fire after the cylinder exploded, Dawn News reported.
The driver survived but a teacher was reportedly killed, the BBC reported.
The children, ages 5 to 15, were just a few miles from their school in Gujrat when the compressed natural gas canister exploded.
Police said the fire appeared to have started when the driver of the dual-fuel vehicle switched from compressed natural gas to gasoline.
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