The Philippine military says three air force personnel were killed when a helicopter carrying supplies to troops fighting militants on a southern island crashed after its engine failed.

Regional military spokesman Lt. Col. Randolph Cabangbang says the Vietnam War-vintage UH-1H Huey helicopter lost engine power as it approached a military camp in Patikul township on Jolo island Saturday. The helicopter hit the ground hard and rolled down a hill. Three crew members were killed and the fourth was injured.

The Huey is the Philippine air force’s workhorse and is used extensively in troop deployment, resupply and disaster operations. The troops are battling the al-Qaeda-linked Abu Sayyaf group, which is on Washington’s terrorist list.

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