Major drug tunnel found on US-Mexico border in California

Mexican federal police said the tunnel extends about 2,600 feet (800 meters) and is lit, ventilated, equipped with a rail car system, and lined with metal beams to prevent collapse. (Mexico Federal Police via AP)

U.S. authorities say 12 tons of marijuana have been seized and 22 people arrested in connection with a cross-border tunnel to Mexico that runs the length of eight football fields.

The U.S. attorney's office in San Diego said Thursday that the passage connecting warehouses in Tijuana, Mexico, and San Diego was lit, ventilated and equipped with a rail system.

Six people were arrested in the U.S. and 16 in Mexico following raids on Wednesday. Two tons of marijuana were seized in the U.S. and 10 in Mexico.

U.S. authorities say smugglers moved the first load of drugs on Wednesday and that they are confident nothing got through undetected.

U.S. Homeland Security Investigations began investigating in May.