A smuggling tunnel running from Tijuana in Mexico to San Diego in the United States, equipped with lighting, ventilation and an electric rail system, has been uncovered by US authorities. It is one of the most sophisticated secret passages to be discovered along the US-Mexico border.
Three men who authorities claim worked as drivers have been charged with possession of marijuana and cocaine with intent to distribute. They face prison sentences of between 10 years and life if convicted.
Authorities who found the underground network seized 8.5 tonnes of marijuana and 148kg (327lb) of cocaine. The tunnel – dug 11 metres (35 feet) underground, 1.3 metres high and 1 metre wide – was shut down before the drugs could be distributed.
The tunnel, which zigzags the length of nearly six football fields, links warehouses in Tijuana and San Diego's Otay Mesa – an industrial area filled with nondescript warehouses, convenient for loading trucks with drugs.
Federal agents had the San Diego warehouse under surveillance after being tipped off by an informant who told them operators bought drills and other construction equipment in August and September.
As US border security has heightened on land, Mexican drug cartels have turned to ultralight aircraft, small fishing boats and tunnels to smuggle drugs. More than 75 underground passages have been discovered along the border since 2008, designed largely to smuggle marijuana.
The tunnels are concentrated along the border in California and Arizona but San Diego is particularly popular because its clay-like soil is easy to excavate. The tunnel is the eighth major passage discovered in San Diego since 2006, a period during which Mexico's Sinaloa cartel has solidified its hold on the prized smuggling corridor but according to authorities, is the first in the San Diego area that was found to be used for cocaine.
Some of the largest tunnels have been discovered following central Mexico's marijuana October harvest, which challenges drug cartels to quickly get their product to consumers.
In November 2011, authorities found a 500-metre tunnel that resulted in seizures of 32 tonnes of marijuana on both sides of the border, with 26 tonnes found on the US side, accounting for one of the largest busts in US history. The tunnel was equipped with electric rail cars, lighting and ventilation and planks lining the floor.