South Yemen intelligence office was assaulted on Wednesday in coordinated attacks in which at least three people were killed, police said.
Witnesses and security sources said attackers on motorcycles roared into the police headquarters and the office of an intelligence agency handling political security in the town of Zinjibar. They opened fire as officers gathered in ranks for the morning roll call.
"A large number of gunmen attacked the political security and the General Security (police) offices at the beginning of the workday. Security guards fired on them, and there are dead and wounded on the scene," a police source said.
Police said al-Qaeda may be behind of the attacks.
Witnesses reached in Zinjibar told Reuters they saw five people believed dead on the street. They added that after the attack and subsequent clashes, the gunmen sped away on their motorcycles.
A doctor at a hospital in the Abyan province where the wounded were taken confirmed three deaths and said at least nine others were wounded, most of them security agents. A security source said the dead included an attacker and two security men.
Yemen's Western and Saudi allies want Sanaa, trying to cement a northern truce and quell southern separatism, to resolve domestic conflicts and consolidate power so that it can focus on fighting al Qaeda.
Yemen escalated a crackdown on al Qaeda this year, and further stepped up security measures after accusing al Qaeda of being behind the June attack.