The drone-fired missiles hit the vehicle near the Angore Adda border town of South Waziristan, the officials said, speaking on condition of anonymity because they were not authorized to speak to the media.
The victims were the associates of Maulvi Nazir, a prominent militant commander in the region, according to the officials.
South Waziristan was the main sanctuary for the Pakistani and foreign militants until the military launched an offensive there in 2009.
The region has also witnessed scores of American drone attacks.
The latest strike comes amid increasing tensions between Pakistan and the United States following a recent claim by top U.S. military officer, Adm. Mike Mullen, that Pakistan's main spy agency backed militants who carried out attacks against American targets in Afghanistan.
It also came a day after Pakistani politicians at a conference in Islamabad rejected the U.S. allegations.
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