Police have discovered a sophisticated drug smuggling tunnel the length of two football fields running beneath the Arizona border with Mexico, and arrested three suspects, authorities said on Thursday.
The tunnel measuring 240 yards (220 metres) linked a building in San Luis, a small town in far western Arizona, to an ice plant in the Mexican border city of San Luis Rio Colorado, the U.S. Drug Enforcement Administration said in a news release.
The clandestine passageway descended more than 55 feet (17 metres) into the ground and measured six feet (1.8 metres) in height. It was equipped with lighting and ventilation, and was the first ever discovered in the small border city south of Yuma.
The non-descript, single-story building in San Luis had been under surveillance since January, after agents noted suspicious comings and goings there. A vehicle stop traced back to the building yielded 39 pounds of methamphetamine, DEA said.
The nationality of the three suspects arrested was not immediately available.
Under pressure from tightened security along the nearly 2,000-mile (3,200-km) southern border in recent years, cash-flush Mexican cartels have increasingly resorted to boring tunnels, particularly to Arizona and California, where geological conditions are favorable.
In the past 10 years, 89 cross-border tunnels have been discovered in Arizona and 50 in California, according to DEA figures.
Late Wednesday night, Mexican troops discovered an incomplete tunnel that began in a warehouse in Tijuana and extended 200 yards toward a San Diego, California, warehouse district, but did not breach the U.S. side of the border.