Al Shabaab militants were reported to have fired a volley of mortar shells at a military base belonging to the African Union forces in Lower Shabelle region on Wednesday night.
The attack began after the militants tried to storm the base near Laanta-Buuro village, according to the residents. AMISOM troops responded to the shelling with similar mortars.
The two sides have traded mortar bombardment for about an hour and there were reports of casualties as result of the attack, but the number has not been confirmed so far.
Neither Al Shabaab nor AMISOM has commented on the assault.
The militants have intensified attacks against AMISISOM and Somali troops in the region as they attempt to topple the UN-backed Somali Federal government based in Mogadishu.