The ambushes came hours apart on May 6 in North Waziristan district, a former Taliban stronghold, said the officials who spoke on condition of anonymity, adding that the attackers then fled toward the border with Afghanistan.
The Pakistani Taliban, the Tehrik-e Taliban Pakistan (TTP), claimed responsibility for the attack. A self-proclaimed spokesman for the group told RFE/RL that the TTP will continue targeting security forces.
The twin attacks come days after a cross-border incursion by dozens of militants killed three soldiers in North Waziristan.
Pakistan and Afghanistan share a rugged 2,400-kilometer-long border and regularly accuse each other of not doing enough to curb the flow of militants in the border region.