Mexican army soldiers discovered a drug-smuggling tunnel in the northern border city of Nogales, media outlets said.
The passage, which extends 56 meters (184 feet), is equipped with water and ventilation systems, El Impartial newspaper reported, citing a statement from the command of the 45th Military Zone.
Troops found the tunnel on Thursday after authorities received an anonymous tip about suspicious activity at a home in the Buenos Aires neighborhood of Nogales.
The tunnel’s entrance is inside the house, where soldiers found a handgun and ammunition. At the far end of the passage, a metal hatch covered the exit to U.S. territory in Nogales, Arizona.
Last month, the army found a tunnel nearly twice as long in the Buenos Aires district. That structure had ventilation and electricity.
Mexican authorities uncovered three other “narco-tunnels” in Nogales in the course of 2012, among the dozens of passages found along the U.S. southwestern border in recent years.