Federal authorities in the United States and Mexico said they'd located an unfinished smuggling tunnel this week during a border sweep in Nogales, Ariz.
The unfinished tunnel originates in Mexico and extends 133 feet into the United States, U.S. Customs and Border Protection said in a statement.
Officials said the tunnel, which is 3 feet high, did not yet open into the United States. Border agents were tipped off to its existence after they observed freshly disturbed dirt within the channel floor of a drainage system.
Tunnels have been a consistent problem at the border, and officials said they work regularly to thwart their construction before contraband or people can be smuggled into the country.
In October 2013, authorities found a sophisticated secret tunnel between Tijuana, Mexico, and California that was so elaborate it was equipped with electricity, ventilation and its own rail system.