Union: Border agents opened fire on each other

The two sets of agents approached an area where a sensor had been activated early Tuesday from different directions and encountered each other in an area of heavy brush, National Border Patrol Council president George McCubbin said.

Agent Nicholas Ivie apparently opened fire first and wounded one of the other agents but was killed in the return fire.

"I don't know what it was he saw or heard that triggered this whole event," McCubbin said. "Unfortunately it resulted in his death and another agent injured."

Acting Cochise County Sheriff Rod Rothrock confirmed the scenario but would not say if Ivie was the first to shoot, saying that was up to the federal agencies involved.

The new details add to a FBI statement Friday that the shooting appeared to be a friendly fire incident that involved no one but the agents.

Sensors are set up in different areas along the U.S.-Mexico border to detect smugglers or illegal immigrants, with Border Patrol agents responding when they're set off. The shooting occurred in a rugged hilly area about five miles north of the border near Bisbee, Ariz., an area known for illegal trafficking.

McCubbin and Rothrock both said the two sets of agents knew the others were heading to the area on foot but apparently didn't know they were so close. McCubbin said he'd been briefed by the agency, while Rothrock's agency has been involved with the investigation.

"It was dark, very, very rugged terrain, and what they could see of each other was further obscured by the fact that there was brush and cacti and stuff like that between them," Rothrock said. "I have no doubt that these agents were in as heightened a state of alert as you can get due to the proximity to the border and the history of trafficking in that area."

Rothrock said that when the agents spotted each other in the dark, "they apparently took defensive postures, which was probably interpreted as aggressive postures. Like readying your weapons, for example."