The official did not immediately know who had carried out the attack, but the US is supporting Somali partners as they target Islamic Al-Qaeda militants aligned with the Shabaab group.

"There was an attack in Jubaland, Somalia and it resulted in one US killed, four US wounded and one partner wounded," the official said.

American forces under the US military's Africa Command are partnering with African Union Mission to Somalia (AMISOM) and Somali national security forces in counterterrorism operations, and have conducted frequent raids and drone strikes on Shabaab training camps throughout Somalia.

Last year, a member of the Navy SEALs was killed in a nighttime attack in Somalia, marking the first US military combat death there since the infamous events of "Black Hawk Down" in 1993, when 18 American servicemen died in what is called the Battle of Mogadishu.

Since 2007, Al-Shabaab has been fighting to overthrow the internationally backed government in Somalia.