The attack happened near a roadside restaurant at Pindi Gheb, near Attock about 60 kilometres (40 miles) from Islamabad.
"The gunmen first opened fire on the tankers and after fleeing they attacked a nearby police post in which three police constables and one sub inspector were killed," local police official Sajid Mehmood told AFP.
"Six other police officials were wounded," he added.
The gunmen also fired rockets and the police post was gutted in the attack with the fire brigade trying to put out the blaze that had engulfed the six NATO vehicles, which included oil tankers and supply trucks, he said.
NATO trucks and tankers are targets of frequent attacks in Pakistan blamed on Taliban and other militants attempting to disrupt supplies bound for more than 130,000 US-led international troops fighting in Afghanistan.
Most supplies and equipment required by the soldiers in Afghanistan are shipped through Pakistan, although US troops increasingly use alternative routes through Central Asia. (*)
Editor: Kunto Wibisono
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