An investigative report into the fatal friendly fire shooting of a U.S. Border Patrol agent in Arizona shows that agents were in radio contact and in close proximity to each other just before they fired their weapons.

Agent Nicholas Ivie was killed Oct. 2 in a remote location near the Mexican border. He was responding to reports that a sensor that detects movement in the area had been tripped.

Two other agents also responded, and authorities say the agents fired on each other somehow.

Ivie died at the scene. Another agent was wounded. A third wasn't injured.

A Cochise County sheriff's office report released Friday indicates the agents were in radio contact with each other and close enough to signal their presence with a flashlight.

The FBI declined to comment.