PHOENIX (AP) — Federal police have arrested two men who may be connected with the fatal shooting of a U.S. Border Patrol agent just north of the Mexico-Arizona border, a Mexican law enforcement official said Thursday.

The official, who spoke on condition of anonymity because he was not authorized to release the information, said it was unclear if there was strong evidence linking the men to the shooting of Agent Nicholas Ivie.

Ivie and two other agents were fired upon Tuesday in a rugged hilly area about five miles (eight kilometers) north of the border near Bisbee, Ariz., as they responded to an alarm that was triggered on one of the sensors that the government has installed along the border.