Investigators are considering whether Border Patrol agent Nick Ivie, his wounded colleague, or both were victims of friendly fire in the Tuesday shooting that left Ivie dead, sources have confirmed to the Arizona Daily Star.

Ivie was killed and the other agent was wounded but is out of the hospital.

Acting Cochise County Sheriff Rod Rothrock said friendly fire cannot be ruled out at this time.

Though he emphasized that it is still early in the investigation, he said friendly fire is a possible explanation.

"Gunfight situations are highly fluid and dramatic, and this was out there in the middle of the night," said Rothrock. "People are moving and running, and I can't say it didn't happen."

If it was friendly fire, that conclusion will be reached later in the investigation, he said.

The news of the possibility of friendly fire emerged on the same day Mexican authorities publicly acknowledged they have two possible suspects in custody who were arrested south of the border, east of Naco, Sonora.

While they were arrested a few miles south of the shooting scene a few hours after it happened, investigators have so far not confirmed any connection to the shootings.

“This happened in a really dangerous area,” said attorney Sean Chapman, who is representing the wounded agent. “They were pursuing drug smugglers that were probably armed.”

Asked whether friendly fire was a possibility, Chapman said, “I don’t believe anyone involved in the investigation thinks anyone (in Border Patrol) committed a crime.”

The explanation of the shooting "is probably going to come down to forensics," Chapman said.

It's routine that any agent involved in a shooting incident gets legal representation, he said.