Islamabad, Pakistan (CNN) -- Sixteen people -- including five children -- died when an oil tanker carrying fuel for NATO exploded Saturday morning in Khyber Agency, a district in Pakistan's volatile tribal region bordering Afghanistan, a government official said.
A remote-controlled bomb caused the explosion, said Shafeer Ullah Khan, a top government official of Khyber Agency.
Khan said the bomb was planted under the oil tanker, which exploded when the vehicle was about 8 kilometers (5 miles) east of Afghan border.
Khan said when the people in the area gathered to collect oil leaked from the tank, it caught fire and killed the 16 people.
A NATO spokesman said the alliance won't be commenting.
Khan said in another incident on Friday evening, nine oil tankers carrying fuel for NATO caught fire after a planted bomb was also detonated by a remote control at Torkham, at the Pakistan-Afghanistan border. He said the oil tankers were parked at the border waiting their turn to enter in Afghanistan.
It was not immediately clear who was behind either attack.
In the past year, dozens of oil tankers carrying fuel for NATO forces in Afghanistan have been attacked in Pakistan. Militants in the region have frequently targeted Pakistani security forces and supply trucks headed for Afghanistan in an effort to undermine U.S. and NATO efforts there.
At least 29 people have died in such attacks since October.
The tankers are often operated by contracted Pakistani firms hired by NATO, using Pakistani equipment and drivers.