MEXICO CITY (AP) — The Mexican army said Thursday that soldiers patrolling along the Rio Grande river have found an unfinished tunnel that was apparently dug under the river bed in a bid to reach U.S. territory.

Predictably, the tunnel flooded and was found partly full of water. The army said a small pump was found at the mouth of the structure and was apparently used to clear water from it.

Photos distributed by the army showed the builders had tried to shore up the walls of the shaft with timbers that appeared to be buckling.

The army said the tunnel was found earlier this week near the city of Matamoros, across the border from Brownsville, Texas. The tunnel was apparently used for illegal activities.

The river, known in Mexico as the Rio Bravo, is a frequent crossing point for drugs and migrant smuggling.

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