Mokena Soldier, 19, Killed by Apparent Friendly Fire in Afghanistan

A 19-year-old Mokena man was one of five killed by friendly fire in southern Afghanistan.

Aaron Toppen died in what could be one of the worst friendly fire incidents involving the United States and coalition troops since the war in Afghanistan began 14 years ago, ABC7 reports. 

Officials stated Toppen's unit had just returned from a security operation in Zabul province's Arghandab district when attacked by insurgents. The U.S. troops were mistakenly hit by their own air strike, according to Reuters.

"The casualties occurred during a security operation when their unit came into contact with enemy forces," the U.S-led coalition said Tuesday. "Tragically, there is the possibility that fratricide may have been involved. The incident is under investigation."

Toppen graduated from Lincoln-Way East High School last year. He departed for Afghanistan in March, a month after the the death of his father Ronald Toppen, Sun-Times Media reports.

"Aaron was a funny, caring, loving kid,” his sister Amanda Gralewski told Sun-Times reporters. “He loved to fish. He loved his friends. He loved being outdoors. He loved his family. He would give the shirt off his back for anyone.”