Yemeni security officials say an airstrike targeting a vehicle traveling through the country's east has killed at least four suspected militants.

The officials say the attack happened Sunday outside the city of Marib. Officials and local witnesses say the strike was carried out by a U.S. drone. They spoke on condition of anonymity because they were not authorized to talk to the media.

The U.S. considers the local al-Qaida branch the world's most active and has used drones in the past to go after its members. A senior al-Qaida member was killed earlier in October in a similar airstrike in the eastern Shabwa province.

Yemen's government has intensified its campaign against militant groups with the help of U.S. advice and logistical support. Militants have carried out attacks in retaliation.