Four people riding on two motorbikes shot dead the driver and then set fire to the vehicle in Mian Ghundai suburb of the provincial capital Quetta, local police officer Fareed Waraich told AFP.
The driver's helper jumped out of the vehicle which was totally gutted, he said adding that the body of the driver was charred beyond recognition.
"The driver apparently received fatal injuries and could not escape," the official said adding that the attackers fled on their motorcycles.
No group has claimed responsibility for the blast but the Taliban has in the past said it carried out similar attacks to disrupt supplies to the more than 130,000 US-led international troops fighting in Afghanistan.
Taliban and Al-Qaeda-linked militants frequently launch attacks on NATO supply vehicles in the northwest and southwest Pakistan bordering landlocked Afghanistan.
Most supplies and equipment required by foreign forces in Afghanistan are shipped through Pakistan, although US troops increasingly use alternative routes through Central Asia.
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