A relative says a 25-year-old soldier from Ohio was among five American troops killed in an airstrike in southern Afghanistan.

The cousin says military representatives went to the home of Justin Helton's parents in Beaver, Ohio, early Tuesday to inform them of their son's death.

A Pentagon spokesman says that the five troops were killed Monday during "a security operation" and that the likelihood friendly fire caused their deaths is under investigation.

Mindy Helton says her cousin specialized in dealing with explosives and was based out of Fort Bragg, North Carolina.

She says he had been in Afghanistan about two months and was engaged to be married. He had been in the Army since 2010.

In Illinois, the family of 19-year-old Aaron Toppen says they also learned of their relative's death in the airstrike.