A U.S. Marine was killed in a skirmish with Islamic State in northern Iraq on Saturday, making him the first American combat casualty in an attack by the extremist group in that country, U.S. and Iraqi officials said.

A U.S. Marine was killed in a skirmish with Islamic State in northern Iraq on Saturday, making him the first American combat casualty in an attack by the extremist group in that country, U.S. and Iraqi officials said.