The militant fighters attacked a forward operating base in Buulo Mareer, about 120 kilometers southwest of Mogadishu, the African Union Transition Mission in Somalia (ATMIS) said in a statement as quoted by CNN.

According to reports, the attackers were seen using  Vehicle Borne Improvised Explosive Devices and suicide bombers while conducting the attack.

The casualty figure is still not known.

US State Department has condemned the incident and said in a statement: " The United States strongly condemns today’s attack by Al-Shabaab in Buulo Mareer on the Ugandan peacekeeping forces deployed to the African Union Transition Mission (ATMIS) in Somalia.  We express our deepest condolences to the victims’ families and friends and wish a full recovery to those injured."

" The United States commends the bravery and sacrifice of the troops participating in this important mission.  We stand with our Somali and African Union partners in the fight to defeat terrorism and to advance peace and stability for the Somali people," read the statement.