The identity of the officer has not been made public but the source said the officer was a former Navy SEAL.
The death comes as the Trump administration is making plans to withdraw more than 600 troops from Somalia in the near future.
US Special Operations forces have been embedded with the Somali National Army, assisting in the fight against the militant group Al-Shabaab. As well as advising on airstrikes and ground assaults, the Navy SEAL-led team’s primary task is to train and build Somalia its own elite light infantry force.
The CIA declined to comment.
The New York Times first reported the death of the officer.
This story is breaking and will be updated.