Baghdad — Assailants fatally shot an American aid worker Monday in a rare killing of a foreigner in the Iraqi capital in recent years, U.S. and Iraqi officials said. The man, whom the U.S. Embassy in Baghdad identified as 45-year-old Stephen Edward Troell, a native of Tennessee, was killed by unknown assailants in his car as he drove onto the street where he lived in Baghdad's central Karrada district on the east bank of the Tigris River. Police said the man's wife and child were in the car with him but were not hurt.