Pakistani authorities say an unknown gunman has killed three foreign militants in a semi-autonomous tribal region bordering Afghanistan. Security officials say the incident occurred on Thursday in North Waziristan. They say one of the dead is believed to be an Arab and the other two are Uzbeks. The attacker managed to flee the scene. It was not immediately clear who the gunman was or what was his motive. But local government officials say a dispute among the militants could have triggered the shooting. Pakistan's military has been trying to flush out foreign militants from the region since last March. The area is also considered a possible hideout for al-Qaida leader Osama bin Laden.