Almost 30 tankers carrying fuel for NATO forces in Afghanistan have been destroyed in southern Pakistan.
The attack in the town of Shikarpur in Sindh province on Friday came a day after three Pakistani soldiers died in a cross-border air strike by NATO.
Pakistan has blocked supply routes for US and NATO troops in Afghanistan following the incident on Thursday.
Hundreds of NATO supply tankers have been destroyed by insurgents in Pakistan over the last few years.
However, the BBC reports this was the first one in this part of Sindh.
District police chief Abdul Hameed Khosa told the BBC that up to 15 gunmen armed with rocket launchers and assault rifles, were involved.
Attacks on NATO supply convoys are rare in southern and central Pakistan, so security forces do not provide the escort that is routine in the north-west of the country.