TUCSON, Ariz. (AP) — Four Mexican soldiers crossed into Arizona and held a U.S. Border Patrol agent at gunpoint before realizing where they were and returning to Mexico, federal authorities said Wednesday.

The confrontation occurred early Sunday on the Tohono O'odham Indian Reservation, about 85 miles southwest of Tucson, in an area fenced only with barbed wire, said Dove Crawford, a spokeswoman for the Border Patrol.

The soldiers, outfitted in desert camouflage, pointed their rifles at the agent and shouted at him not to move, Crawford said. They lowered their weapons after about four minutes when the agent convinced them about who he was and where they were, she said. The soldiers then retreated into Mexico.