MEXICO/US: A cross-border tunnel between Mexico and the US, spanning nearly half a mile from a nondescript industrial building in Tijuana to a warehouse in Otay Mesa, California, is believed to be the longest illegal tunnel discovered along the southwest border, US federal authorities have said.
Stacked near the tunnel - a deep passage equipped with lighting, ventilation and a pulley system - authorities found more than two tonnes of marijuana.
The tunnel is more than 730m (2,400ft) long, roughly eight American football fields in length, and roomy enough for people to run through.
"This one is just absolutely amazing, it's just huge," said Michael Unzueta, special agent in charge of Immigration and Customs Enforcement in San Diego. "It really looks like a professionally done mine shaft."
US and Mexican authorities, who have unearthed several tunnels in recent years, have secured its entry and exit as investigators continue to gather evidence and to research the operators of the buildings.
Authorities said the tunnel, found on Thursday, was probably the work of a powerful drug cartel. It is unknown how long it has been in operation.
Soil and air samples are being analysed to determine if anything aside from drugs was transported through the passage, including weapons. Authorities have long been concerned that such subterranean passages could be used to pass high-powered weaponry or terrorists into the country.
Since 1990, about three dozen tunnels have been discovered along the border, most of them crudely built, but many exhibiting impressive feats of engineering. Entrances have been hidden under lift-up staircases, fireplaces and pool tables and some connected to storm drains.
Authorities found the Otay Mesa tunnel through a tip-off.
A pulley system was used to lower the contraband down a 15m (50ft) shaft into the tunnel on the Mexican side. A pumping system kept water from accumulating at the bottom of the tunnel, which at times reached depths of 25m (80ft) underground.