SAN DIEGO -- Agents discovered a cross-border tunnel that was apparently used by the Arellano Felix cartel to smuggle drugs into the United States through a remote area of San Diego County.

Drug Enforcement Agents found the tunnel Wednesday morning while executing a search warrant at a house about 70 miles east of San Diego in the U.S. community of Tierra del Sol near Boulevard, The San Diego Union-Tribune reported.

The 1,200-foot tunnel, which is wood-framed and equipped with electric lights and a ventilation system, begins in Mexico on the outskirts of Tecate under a fireplace in a ranch house located about 200 feet from the border fence, the newspaper reported.

Its opening on the U.S. side of the border is in an unoccupied house. The couple who own the house, Belinda and Raul Alvarado, are not believed to be involved in drug smuggling, Errol Chavez, special agent in charge of the DEA in San Diego, told the newspaper.

The home had been owned previously by Elbert Lushen Johnson, who was arrested in September 2000 in Arkansas on suspicion of transporting cocaine, the newspaper reported.

The Tierra del Sol house was seized in the 1980s because of drug-smuggling activity and sold at public auction, Chavez said.

Officials said the DEA agents who discovered the tunnel did not make any arrests but they found about 600 pounds of fresh marijuana, which indicated that the tunnel had been used recently.

"There's a good possibility that tons of drugs were moved through this tunnel," Donald Thornhill Jr. of the DEA said.

Authorities believe the tunnel has been in place for several years and whoever used it was associated with the Arellano Felix cartel.

"For them to use this tunnel, it had to be under the control of the Arellano Felix organization," Chavez said.