Local media reports two missiles were fired from unmanned U.S. aircraft.
A Pakistani security official in the northwestern Pakistani city of Peshawar, speaking on condition of anonymity, said the drone strike's target was a militant compound and those killed were insurgents, News Pakistan news agency reported Thursday.
Local media reported that one missile hit a house in the Tappi area of Miranshah, North Waziristan's major city, while the other hit a vehicle parked outside the zone of attack.
"It was a militant compound being used to store arms and ammunition. Three militants were killed," the security official said. "The casualties were not high because there not many militants inside."
The covert U.S. UAV attacks are increasingly unpopular in Pakistan, with the Pakistani government stating that they violate national sovereignty but U.S. officials insist that they are a crucial weapon against militants.