A suspected US airstrike hit Al-Shabaab training base in Burta Kumba approximately 12 kilometres Jamame town in the Lower Jubba region.
According to Somali National Army Radio, the airstrike killed 15 Al-Shabaab militants at training the training camp on Wednesday afternoon.
An unknown number of militants were also wounded in the attack.
Meanwhile, the Somali military on Thursday morning captured four Al-Shabaab operatives in a joint operation with Southwest forces in Awdigle Bay region.
The military said the operation was conducted after a tip-off from the residents that the four militants were in the area.
Al-Shabaab which is linked to Al-Qaeda is fighting in Somalia to overthrow the internationally recognised government and establish strict Sharia law based in their own interpretation.
The militants were driven out of the capital Mogadishu in 2011 by AMISOM and the Somali military but they still control rural areas in central and southern regions, conducting ambushes and planting landmines.