The Latest on a cross-border tunnel discovered in the Southern California desert city of Calexico:

4:25 p.m.

U.S. authorities say a cross-border tunnel ran the length of four football fields from a restaurant in Mexicali, Mexico, to a house in Calexico, California.

Investigators seized the tunnel Wednesday following an investigation that netted more than a ton of marijuana and resulted in four arrests in California and Arizona.

Prosecutors say drug traffickers finished building the Calexico house in December and began smuggling drugs there last month under law enforcement surveillance.

It is the 12th completed drug tunnel that authorities have found along California's border with Mexico since 2006. In the last five years, authorities detected 75 border tunnels, mostly in California and Arizona and many of them incomplete.

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11:30 a.m.

U.S. authorities say they have discovered a secret cross-border tunnel in the California desert.

Authorities scheduled a news conference Wednesday afternoon in a residential area of Calexico, a city of about 40,000 people located 120 miles east of San Diego.

A media advisory from federal authorities says the tunnel links Calexico with the large industrial city of Mexicali, Mexico, but provided no details.

Dozens of tunnels designed to smuggle drugs have been found along the U.S.-Mexico border in recent years. Some have been equipped with hydraulic lifts and electric rail cars.

Mexico's Sinaloa cartel has long controlled drug trafficking along the border in California's Imperial Valley, which offers easy freeway access to Los Angeles and Phoenix.