Mexico's army said it discovered two "narcotunnels" in less than 24 hours on the northeast side of Tijuana, a hardscrabble metropolis located across the border from San Diego.

The first tunnel was located Wednesday night some 200 meters (655 feet) from the border, the military commander in that region, Gen. Gilberto Landeros Briseño, told reporters in the building where the clandestine passageway was found.

He said a small recycling business occupied the building where the tunnel began.

The general said Thursday that the tunnel was discovered thanks to ground reconnaissance operations in the area, noting that one person seen exiting the fake business fled upon noticing the soldiers' arrival and left the door open.

The soldiers proceeded to enter the building to search the premises and discovered in the bathroom the unfinished tunnel, which presumably was to be used to smuggle drugs, weapons and undocumented migrants across the border.

Landeros said the tunnel had been constructed to a point approximately 60 meters (200 feet) from the border.

The tunnel was one meter in width, 1.7 meters in height and as much as 10 meters deep and had lighting and an unsophisticated ventilation system.

Authorities confiscated two tractor-trailers as well as different excavation tools such as shovels, picks and wheelbarrows.

On Thursday night, military officials in that region said in a statement that a second narcotunnel had been found at a property also located on the northeast side of the city, where 50 tons of marijuana were seized.

That 350-meter-long (1,150-foot-long) tunnel was discovered thanks to ongoing military operations in the area, the statement said.

Since the mid-1990s, authorities have discovered many clandestine passageways along the U.S.-Mexico border, with dozens of narcotunnels having been found in the past four 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). EFE