Pakistani officials say militants overnight ambushed security forces who were responding to an earlier attack on aid trucks in the country's troubled northwest, leading to a shootout in which four troops were killed.

Militants armed with guns intercepted several passenger buses on a highway in the restive southwestern Pakistan late Tuesday night, forcibly removed seven passengers and killed them before fleeing the scene,

Gunmen in northwestern Pakistan killed a driver and a security official on Monday when they ambushed a convoy of trucks carrying food, medicine and other supplies for thousands of residents trapped by sectarian violence,