At least four security officials were killed while two others injured in a landmine explosion in Lower kurram Agency on Thursday morning.
According to sources, a vehicle of the security forces hit a landmine in Shabak area.
A contingent of army men arrived at the scene and cordoned off the blast site.
Orakzai is one of Pakistan s seven semi-autonomous tribal regions in the northwest, where Tehreek-e-Taliban and Al Qaeda-linked militants are said to have carved out strongholds.
Thursday's incident comes as Pakistan is engaged in military offensive in the tribal regions of North Waziristan and Khyber and is likely to expand its anti-terrorist onslaught to more areas in the aftermath of the attack on Army Public School in Peshawar.
Earlier on Wednesday, army s helicopter gunships destroyed four militant hideouts in Dattakhel area of North Waziristan, killing as many as 12 terrorists.
