Three US airmen were killed while performing combat operations north of Baghdad, the American military said Friday. All three, assigned to the Air Force Office of Special Investigations, died Thursday near Balad Air Base, some 80 kilometers (50 miles) north of Baghdad, the military said in a statement. The victims' names were withheld pending family notification. The brief statement did not give details on how the airmen died, nor whether they died in aircraft or on the ground. No air crashes, emergency landings or shootings were reported Thursday or Friday.