The shooting death of a Border Patrol agent along the Arizona-Mexico border may have been the result of friendly fire. The FBI said a preliminary investigation indicates the death of one agent and the injury of another "were the result of an accidental shooting incident involving only the agents."

NPR's Ted Robbins tells our Newscast unit the FBI was investigating the possibility of friendly fire and that today Homeland Security Janet Napolitano flew to Arizona to review the case and meet with the dead agent's family.

He filed this report from Bisbee, Ariz.:

"Secretary. Napolitano met with the family of agent Nicholas Ivie then toured the scene of the shooting in rugged hills five miles north of the Mexican border. She did not say anything publicly, but law enforcement officials have acknowledged they are investigating whether one or more border patrol agents fired their weapons at each other in the mistaken belief that they were being fired upon by other."Ivie was killed, a second agent was wounded, a third agent was not hit. It was night and the agents were responding to suspected smugglers in the area."

NBC Newsgoes a step further in its report saying that investigators are "preparing to announce" that Ivie was killed by accidental gunfire.

"The conclusion is based on an analysis of the ballistics, the lack of evidence of other criminals in the area at the time, and other factors," NBC reports citing unnamed "state and federal officials."

As Mark reported Tuesday, the agents were on horseback and were responding to tripped sensors that indicated something was moving in the area.

Update at 8:22 p.m. ET. FBI Issues Statement:

In a statement, FBI Special Agent in Charge James L. Turgal Jr. said:

"While it is important to emphasize that the FBI's investigation is actively continuing, there are strong preliminary indications that the death of United States Border Patrol Agent Nicholas J. Ivie and the injury to a second agent were the result of an accidental shooting incident involving only the agents.

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