A Pakistani official says gunmen have shot and killed one of his staff and wounded three security guards in the restive tribal region along the Afghan border.

Mohammad Ayaz Khan, the top administrator in North Waziristan, says Hamidullah Khan's vehicle was ambushed in a mountainous area late Friday night, and that a fourth guard is missing. The two are not related.

Hizbul Ahrar, an offshoot of the Pakistani Taliban, claimed responsibility for the attack.

A number of tribal officials have been assassinated in recent months as residents return to the area following a yearslong military offensive aimed at rooting out extremist groups.