The death toll in an al-Qaida terrorist attack against an army headquarters in Yemen's southern port city of Aden on Wednesday has risen to 16, including five soldiers, a government official and medics told Xinhua.

"Two coordinated attacks that targeted the headquarters of the Fourth Military Region in Aden this morning has killed 16 people and injured dozens of others including civilians and passers-by," the government official said, requesting anonymity.

Fierce clashes that followed the attack left about six Al-Qaeda members, five soldiers and five civilians killed, including women and children, the source said.

Local medics confirmed the casualties to Xinhua, saying " several injured soldiers who are in critical conditions have been evacuated for medical treatment to the Yemeni capital Sanaa while the others are in hospitals in Aden."

Scores of masked attackers from the Al-Qaeda group stormed the army headquarters in the coastal district of Tawahi, army officers said.

"We heard a huge blast and heavy gunshots and immediately they started shooting at us. Those who attempted to escape were shot from behind. Heavy fighting erupted inside and around the army base," an army officer told Xinhua.

A police officer in Aden said the Al-Qaeda gunmen entered the army base through the rear door, and spread bullets and rocket propelled grenades at the main gate during the morning service.

The army headquarters was sealed off by armored vehicles and heavy reinforcements from special security forces in Aden as criminal police officers were searching for evidence.

Earlier in the day, a police source said that gunmen suspected to be Al-Qaeda members invaded the headquarters of the Fourth Military region in Aden.

He said about five soldiers including high-ranking military personnel were confirmed died in the bloody attack.

No group has claimed responsibility for the armed attack against the military base in Aden and Yemeni government authorities have yet to comment.

Last month, al-Qaida militants killed 24 Yemeni soldiers of the Special Forces in an attack on a military barracks in the southeast province of Hadramout.

Militants of the Yemen-based Al-Qaeda offshoot were blamed by the country's government for a series of assassinations and armed attacks, mostly in the country's southern regions.

The 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.