<p><br /> Customs officials are investigating after two tunnels used to smuggle drugs from Mexico into the US were discovered.<br /> </p><p><br /> The cross-border tunnels - housed in warehouses in San Diego's Otay Mesa industrial area - were used to smuggle huge amounts of marijuana from Tijuana, Mexico.<br /> </p><p><br /> They run for about 2,000 feet (600 metres) and were equipped with rail car, lighting and ventilation systems.<br /> </p><p><br /> According to US authorities, both were the work of Mexico's Sinaloa cartel, headed by that country's most-wanted drug lord, Joaquin "El Chapo" Guzman.<br /> </p><p><br /> The discoveries produced some of the largest marijuana seizures in the United States.<br /> </p><p><br /> Immigration and Customs Enforcement agent Tim Durst said: "To an extent this is somewhat of a cat and mouse game. As long as there's demand for the supply of drugs in the United States then the drug smuggling organisations will continue to find a way to smuggle drugs into the United States."<br /> </p><p><br /> He added: "They're looking to find new ways to move drugs and we're looking to find the ways that they're moving drugs. Their hope is they get a tunnel completed, they can move a lot of drugs into the United States and get a good return on their investment.<br /> </p><p><br /> "Our hope is we find tunnels or the boats or whatever next they're next going to before they get a return on their investment."<br /> </p>
