Mexican army soldiers found a suspected "narcotunnel" under construction in a northwestern border city, military officials said.

Gen. Gilberto Landeros Briseño, commander of the 2nd Military Zone, said the tunnel runs for 135 meters (440 feet) under the small Mexican city of Tecate, Baja California state, but had not yet been dug to the U.S. side of the border.

The entrance to the underground passage is located inside a bottling plant in the city center, a two-story building without the name of a business entity.

The alleged drug tunnel was discovered after an anonymous tip concerning the presence of people going in and out of the building in a "suspicious" manner, a Defense Secretariat statement said Thursday, citing Landeros.

When soldiers arrived at the scene, an individual removing tools from a vehicle tried to flee but was caught and found with a substance that appeared to be marijuana.

During an inspection of the building, the troops found the entrance to the tunnel, equipped with a concrete floor, lighting and ventilation.

Seven suspects doing construction work on the tunnel also were arrested and turned over to the relevant authorities, the statement said.

Since the mid-1990s, authorities have discovered numerous clandestine tunnels along the U.S.-Mexico border, particularly over the past five years.

People traffickers and drug cartels often use clandestine tunnels to cross the vast U.S.-Mexican border, which runs 3,200 kilometers (1,988 miles)

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