Fronteras

United States and Mexican authorities have discovered a drug-smuggling tunnel that runs between a warehouse in Tijuana and one in Otay Mesa in San Diego.

Warehouse in Otay Mesa, California, where a drug-smuggling tunnel and 20 tons of marijuana were discovered.

Immigration and Customs Enforcement

In this photo provided by Immigration and Customs Enforcement, 20 tons of marijuana were seized by ICE agents in Otay Mesa, California, on November 3, 2010.

Immigration and Customs Enforcement authorities say they discovered 20 tons of marijuana in the warehouse on the U.S. side.

Meanwhile, Mexican soldiers say they confiscated 4.5 tons of marijuana at the tunnel's entrance on their side. Soldiers standing guard outside the two-story cement block building in Tijuana say the tunnel drops about 18 feet under ground before heading beneath the border fence to San Diego.

The building in Tijuana is about a half block from a Pioneer factory, or maquiladora, where electronics devices are assembled for the U.S. The border fence is just on the other side of that factory.

ICE officials say the tunnel isn't tall enough to walk through, so smugglers would have to crawl. ICE officials say the department's national director, John Morton, will tour the tunnel later this afternoon, along with San Diego's U.S. Attorney Laura Duffy and other federal officials.

A massive drug smuggling tunnel was unearthed not far from this one in 2006. It plunged more that 80 feet underground before surfacing inside an enormous warehouse in Otay Mesa and was equipped with lighting, drainage and ventilation systems.

U.S. authorities say drug smugglers have resorted to using tunnels to pass illicit material across the border as border enforcement above ground has gotten tougher.