Six people were killed in an attack on a convoy of NATO tankers carrying fuel for international troops in Afghanistan, according to media reports on Monday.
Twenty-eight tankers burst into flames from the attack, the Pakistan broadcaster Geo TV reported on its website.
Unknown attackers opened fire on the tankers late Sunday at an industrial site in Pakistan's capital, Islamabad. Another six people were injured in the attack, according to Geo, which cited rescue workers.
The attack follows the destruction by insurgents Friday of another convoy of 27 fuel-carrying tankers for the NATO troops, which receive much of their supplies overland via Pakistan.
The Pakistan government on Thursday shut down one of the most heavily-travelled supply routes for NATO convoys in retaliation for the increasing number of attacks by Afghanistan-based NATO units on targets in the border region with Pakistan that serve as a base for militant groups in Afghanistan.
In September, the US Central Intelligence Agency (CIA) carried out at least 21 drone strikes on suspected Taliban strongholds in the mountains of Pakistan - the highest of any month, The New York Times reported last month. The next highest monthly total was 11 strikes, in January.
At least 123 alleged militants including some foreign fighters linked to Al Qaeda have been killed in the CIA-operated attacks.