Quoting unnamed government sources, Geo television reported that a Pakistani soldier was also killed in the offensive on Saturday night.
Military spokesman Major-General Shaukat Sultan said an incident had taken place in the North Waziristan tribal region and details were being gathered. He gave no specific details.
Residents said troops had cordoned off an area near Miranshah, where the incident took place and the main town in North Waziristan, 300km southwest of the Pakistani capital, Islamabad.
The incident occurred two days after US forces based in Afghanistan killed 24 suspected al-Qaida fighters and their Taliban allies in the same region.
Tension has been building for months in North Waziristan since the army completed a string of offensives against alleged al-Qaida insurgents in neighbouring South Waziristan.
Major-General Akram Sahi, military commander in North Waziristan, this week ordered tribesmen to hand over foreign fighters hiding in the region or face an imminent offensive.
A senior US administration official in Washington on Thursday said the United States, Afghanistan and Pakistan needed to squeeze insurgents along the rugged border where al-Qaida leader Osama bin Laden might be hiding.