A drone strike has killed four suspected Al-Qaeda militants in southeast Yemen, a front-line in the U.S. war on the extremist network, a provincial official said Thursday. The attack late Wednesday hit a car in a military camp in Al-Qaeda-controlled Mukalla, capital of the vast desert province of Hadramawt. The official, who did not want to be named, said a local Al-Qaeda chief was among those killed. A second Al-Qaeda vehicle was targeted Wednesday evening in a drone strike in the town of Ghil Bawazir in the same province but there was no word of casualties, he said. Washington has repeatedly targeted militants from Al-Qaeda in the Arabian Peninsula in drone strikes in Yemen. AQAP said earlier this month that its leader Nasir al-Wuhayshi, number two in the global jihadi organization, was killed in one such raid, and named its military chief as his successor. The jihadis have exploited months of fighting between loyalists of Yemen's exiled government and Iran-backed Houthi rebels to consolidate their grip on Hadramawt and its capital Mukalla - a city of more than 200,000. Meanwhile, in the battleground southern city of Aden, four civilians were killed and scores wounded Thursday by mortar fire blamed on the Houthis, according to a medical source.