The incident took place in Karachi, the business hub of Pakistan late last night where a number of other people also sustained injuries.
Officials said most of the bodies could not be identified as they are completely burned and the only way to identify them is through DNA tests.
Officials added that the driver of the van is among the ones killed.
Witnesses said that the only passengers who saved their lives were the ones setting close to the doors and windows but they also sustained injuries while jumping from the van.
Nine passengers injured in the incident were shifted to Jinnah Hospital in Karachi city for treatment, officials said.
The rescue operation was jointly conducted by locals and Pakistan’s motorway police.
Officials said that the van was converted to Compressed Natural Gas (CNG), a more risky alternative for Petrol and Diesel.
In Pakistan and Afghanistan it is cheaper to use CNG for vehicles than Petrol and Diesel.
Such like incidents have also happened in Afghanistan.