Security officials say a gunman on a motorcycle has killed a Yemeni security official employed by the U.S. Embassy in Sanaa.

The officials say the shooter opened fire on a car carrying Qassem Aqlani as he traveled to work on Thursday. The unidentified attacker then fled the area.

Security officials said the attack resembled those carried out by al-Qaida, but that it was too early to say if the group was behind the shooting.

A senior U.S. State Department official said the U.S. is “deeply saddened” by the attack and is working with Yemeni authorities.

Yemen's government has been battling to regain territory from al-Qaida's Yemen branch after militants seized control of parts of the country's south last year.

Suspected militants have carried out suicide bombings and other attacks targeting officials.