Suspected al-Qaida militants attacked a Yemeni intelligence headquarters on Saturday, killing 14 people in a bold attack in the country's main southern city of Aden, officials said.

The attack in the heart of the port city underscored al-Qaida's ability to launch deadly strikes despite a two-month Yemeni military offensive backed by the U.S. that earlier this year dislodged militants who had taken over a string of southern towns near Aden.

Militants attacked the intelligence building from two sides, firing automatic weapons and rocket-propelled grenades, according to intelligence officials in the city and witnesses from the adjacent state TV and radio building. The assault left 11 soldiers and three intelligence officers dead, and six people wounded, the officials said.

They and the witnesses, who are government employees, spoke on condition of anonymity because they were not authorized to talk to the press.

Al-Qaida-linked militants took advantage of political turmoil in Yemen to overrun several major towns in Abyan province, neighboring Aden. They held many of them months until the military drove them out of most areas in May, including the Abyan provincial capital of Zinjibar and the nearby town of Jaar. More than 100,000 people fled the violence there, with many taking refuge in makeshift shelters and schools in Aden.

Many of the militants escaped into nearby mountains, however, and have continued to carry out attacks. Suicide bombings and assassinations have targeted officials in Aden tasked with fighting al-Qaida. An al-Qaida front group, Ansar al-Shariah, was behind the kidnapping of a Saudi Arabian diplomat in the port of Aden in March.

The area sees other violence as well. Earlier this week, gunmen stormed a passenger plane after it landed in Aden and grabbed an opposition leader from his seat and spirited him away to an unknown destination. The masked gunmen burst into the airport building first, meeting no resistance from airport security. They then ran onto the runway and boarded the plane to kidnap retired Maj. Gen. Ahmed Abdullah al-Hassani, a former Yemeni navy commander and a prominent campaigner for the south's secession. It is not clear who was behind the abduction.

The United States considers al-Qaida in The Arabian Peninsula as the terror network's most dangerous offshoot, held responsible for several failed attacks on U.S. territory.