Houthi rebels in a truck past a Ansar al-Sharia flag painted on the side of a hill, in Rada, Nov. 22, 2014.

ADEN — Al-Qaeda fighters retook on Wednesday two southern Yemeni towns they briefly occupied four years ago, residents and local fighters said, exploiting the collapse of central authority in Yemen in its eight-month war.

In an early morning surprise attack on the capital of Abyan province, Zinjibar, and the neighboring town of Jaar, the militants overcame local forces and announced their takeover over loudspeakers after dawn prayers.

Residents identified them as Ansar al-Sharia, a local affiliate of al-Qaeda.

At least seven local militiamen and five militants were killed, according to local fighters. Militants were deployed to the streets of both towns and in Jaar blew up the house of a local commander killed in the fighting, residents said. Schools and shops were closed.

Later on Wednesday, a clinic in the southern city of Taiz run by Medecins Sans Frontieres (MSF) was hit by airstrikes by a Saudi-led coalition, the medical aid group said.

The Saudi-led coalition since March has been trying to defeat Yemen’s Iran-backed Shi’ite Houthis, who captured large parts of the country and wrested control from its government, which only recently returned from exile.

“The entrance of al Qaeda this time happened in the absence of any state institutions, which al-Qaeda exploited,” said Zinjibar resident Fadl Mohammed Mubarak.

Jaar and Zinjibar are about 30 miles east of the main port city of Aden, where President Abd-Rabbu Mansour Hadi is staying after returning from Saudi Arabia last month.

Parts of Abyan including Zinjibar and Jaar fell to Islamist militants in 2011 for over a year as government control waned during Arab Spring protests.