A North Texan was killed Sunday in Iraq in what the Defense Department described as a non-hostile incident.Sgt. Wesley R. Durbin, 26, of Dallas, and Staff Sgt. Darris J. Dawson, 24, of Pensacola, Fla., died in Tunnis, Iraq, according to the government.Durbin was an honors student and 2001 graduate of Dallas Lutheran School. He volunteered in the Civil Air Patrol in high school, then joined the Marines. After he left the Marine Corps, he joined the Army two years ago.Both soldiers served with the 3rd Battalion, 7th Infantry Regiment in the 3rd Infantry Division.The government said the incident is under investigation.