The militants were inside a car loaded with explosive materials when a missile struck the vehicle, Gulf News reported Wednesday.
The defense ministry did not say whether the airstrike was carried out by a U.S. drone or a Yemeni plane.
Tuesday at least five Yemeni civilians were killed and 17 others injured in continuing tribal clashes over possession of an ancient stone.
The clashes have caused massive damage to property, the government said.
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