"Two unknown attackers on a motorcycle opened fire at army colonel Ali Nasser from the 315th Armored Brigade in Seiyun town in the southeastern province of Hadramout, killing him immediately on the spot," the provincial security source said on condition of anonymity.
The assailants managed to flee the scene after conducting the drive-by shooting.
A military intelligence officer confirmed the attack to Xinhua, saying: "two terrorists riding a motorcycle fired bullets on the army colonel after he left his workplace. Police forces are trying to track down the suspect."
Saturday's shooting is the latest in a wave of almost daily attacks and assassinations blamed on the Yemen-based al-Qaida branch in recent weeks against army and intelligence officers in southern Yemen.
The Yemen-based al-Qaida in the Arabian Peninsula, which emerged in January 2009, is considered the most strategic threat to the Yemeni government and neighboring oil-rich Saudi Arabia.