Up to 12 people have been killed and scores wounded in clashes between Somali rebels and militias loyal to the government, Reuters news agency has reported.
Residents said al-Shabaab fighters and members of the pro-government Islamic Courts Union (ICU) exchanged fire along an industrial road in Mogadishu, the Somali capital, late on Thursday.
Sheikh Abdirahim Isse Adow, a spokesman for ICU, said: "The stubborn opposition attacked our fighters and the government soldiers on our side.
"We killed eight of them and injured 30 others in one spot. I am sure more died. We also captured an anti-aircraft missile mounted on a battle wagon from them.
"From our side, four died and six others were injured. Innocent civilians were also
injured," he said.
Hospital sources said 55 people injured in the fighting were admitted.
Al-Shabaab and allied groups control much of southern and central Somalia and want to impose their version of sharia (Islamic law) in the country.
Fighters launch frequent attacks on government targets and African Union peacekeepers.
Since Somalia descended into civil war in 1992, more than 15 transitional governments have come and gone but violence has persisted.