Fighting broke out between Jubbaland forces in collaboration with Kenyan forces and Al-Shabaab militants in Kudhaa Island area of the region.
The heavy fighting came after members of Al-Shabaab launched a major attack on a Jubbaland military base there.
Local sources told Shabelle Media Network that heavy fighting broke out in Kudhaa after the attack, but it was not clear how many casualties were reported.
Al-Shabaab claimed responsibility for the attack, saying it had taken control of the base.
The situation remains tense, and conflicting movements are still being felt in parts of the Lower Juba region of southern Somalia.