Yemeni security officials say suspected militants have killed three air force pilots as they were en route to an air base in the country's south.

The officials say two gunmen on a motorcycle intercepted the vehicle the pilots were traveling in on their way to the base early Wednesday in the southern province of Lahj. The attackers shot the pilots dead, then fled the scene.

The officials say the pilots were air force colonels based in Al-Annad, Yemen's largest base that also hosts a group of U.S. military advisers helping authorities fight al-Qaida's branch in Yemen.

The U.S. considers the terror network's Yemeni affiliate to be its most dangerous offshoot.

The Yemeni officials spoke on condition of anonymity because they are not authorized to speak to the media.