"Regrettably, three of the eleven passengers on board lost their lives. Eight injured officers have been evacuated to Mogadishu for urgent medical attention," the African Union transition mission ATMIS said.
The air disaster happened on Saturday near Baledogle, in the Lower Shabelle region, which is home to a US military airbase.
ATMIS said the casually evacuation training was a joint exercise that involved Somali army officers. An investigation has been launched into the cause of the crash.