Islamic militia have captured the Somali town of Jowhar, which was the last major stronghold of a U.S.-backed alliance of warlords.
Witnesses say fighters loyal to hard-line Islamic courts took control of the town and seized Jowhar's airport in a coordinated attack Wednesday.
Islamic militia members say at least four people were killed and at least 10 others wounded.
The warlords had attempted to regroup in Jowhar after losing a bloody battle for Somalia's capital, Mogadishu, last week.
But three powerful warlords left Jowhar late Tuesday and another alliance leader, Abdi Hassan Awale, defected from the group. Two of the warlords have headed north to the central Somali town of El Burr in a convoy of pick-up trucks mounted with machine guns.
More than 350 people have been killed in fighting between the warlords and Islamists since February.
The United States has not publicly confirmed or denied backing the warlords. But U.S. officials, speaking on condition of anonymity, say Washington provided money for the warlords' self-proclaimed anti-terrorist alliance.
On Tuesday, seven East African nations imposed travel and banking sanctions on warlords involved in the recent fighting.
Diplomatic efforts are under way to forge an agreement between Somalia's U.N.-backed transitional government and the Islamic authorities who now control several key towns and cities.
The government is based in Baidoa, to the west of Mogadishu, and has been too weak to assert its authority over Somalia.
U.S. officials have expressed concern that the Islamists are harboring al-Qaida terrorists.
Some information for this report was provided by AFP, AP and Reuters.