TUCSON, Ariz. (AP) -- Federal authorities say four Mexican soldiers crossed into Arizona and briefly held a U.S. Border Patrol agent at gunpoint before realizing where they were and returning to Mexico.

Border Patrol spokeswoman Dove Crawford says the incident early Sunday on the Tohono O'odham Indian Reservation, about 85 miles southwest of Tucson, was in an area likely fenced only with barbed wire.

She says the soldiers lowered their weapons after about four minutes when the agent convinced them who he was and where they were, then retreated into Mexico.

Crawford says there have been about 40 similar incursions along the entire border this fiscal year.

State Department spokesman Gonzalo Gallegos in Washington says the encounter "stemmed from a momentary misunderstanding as to the exact location of the U.S.-Mexican border."

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