At least 15 Somalis have been killed and another 30 wounded after fighting broke out between clans near the southern port town of Kismayo, according to AFP.
The news agency reported that Friday's clashes erupted when one Somali army unit tried to expel another unit from a rival clan.
Colonel Abdi Hirre, commander of the Marehan clan unit, said: "Heavy fighting has broken out this morning.
"Our forces have gained the upper hand and we are defeating the renegade forces."
"The number of killed is about 15 from both sides ... We have defeated the violent people who attacked the port town of Kismayo," Hassan Dhere, a commander of the Marehan unit, told AFP.
The fighting, between the Majerten and Marehan clans, broke out about 19km north of Kismayo, which is about 500km.
Residents said the clashes centered around the Golweyne area, with both sides exchanging heavy machinegun fire.
Hassan Mohamed Ali, a Marehan clan elder, said: "We have ejected criminals who were ambushing travelers from the Kismayo-Mogadishu road.
"We are still chasing them."
Meanwhile in Mogadishu, an army officer was killed and a second injured when their vehicle was hit by a roadside explosion, the latest in a string of attacks on government, African Union and Ethiopian troops.
Police fired shots in the air and made several arrests, witnesses said.
"The targeted government truck was completely destroyed," Colonel Ali Said, the police chief, said.
Violence has surged in Mogadishu since Somali government troops, backed by Ethiopian forces, ousted the Union of Islamic Courts group in April after months of fighting that left hundreds dead and hundreds of thousands displaced.
Somalia has been without a functioning central authority since the 1991 and the three-year-old transitional government has been unable to assert control.