The latest strike hit North Waziristan, the same tribal district targeted in other drone attacks in the past 24 hours and a renowned hub for Taliban and Al-Qaeda-linked militants.
The target of the fourth drone attack was a compound in the outskirts of Miranshah, the main town in North Waziristan.
“Two US drones fired three missiles. We have reports that six militants were killed,” a security official based in Peshawar told AFP.
Residents in Miranshah said they heard three huge explosions and later the villagers started announcements from local mosques asking for help.