WASHINGTON (October 5, 2012)--The FBI is investigating the possibility that the shooting death of a U.S. border patrol agent and the wounding of another was a case of friendly fire, a law enforcement official says.

The official says the probe is looking into whether the two men exchanged gunfire Tuesday in the mistaken belief that a hostile gunman was firing on each of them.

The shooting occurred near Bisbee, Ariz.

The official spoke on condition of anonymity because the matter is under investigation.

At FBI headquarters, spokesman Chris Allen declined to comment.