At least two Pakistani soldiers were killed and nine more injured when a security forces convoy was targeted with a roadside bomb in the restive North Waziristan tribal region on Tuesday.
The bomb exploded as the convoy was heading to Datta Khel, 45 km from Miranshah, the main town of North Waziristan Agency, journalists in the region said.
One vehicle was completely destroyed by the blast.
Local residents said the security forces opened fire after the attack but there were no reports of any casualties.
Officials earlier said they had defused a bomb on the road.
The attack occurred at a time when authorities had clamped curfew in the area to facilitate the movement of troops.
No group claimed responsibility for the attack.
The main Taliban group in North Waziristan, led by Hafiz Gul Bahadar, has a peace deal with the security forces and denied involvement in the incident.
Security official say several other militant groups, including the Tehrik-e-Taliban Pakistan led by Hakimullah Mehsud and elements of the Punjabi Taliban are active in the region.