Originally published on April 4, 2014

US federal agents have uncovered two drug-smuggling tunnels underneath the US-Mexico border, both surfacing in San Diego-area warehouses and equipped with rail systems for transporting contraband, officials said on Friday.

The discovery led to the arrest of a 73-year-old woman suspected of running one of the warehouses connected to a drug smuggling operation, according to a joint press release made by four federal agencies.

Authorities said the first tunnel was about 600 yards long and furnished with lighting, a crude rail system and wooden trusses and connected a warehouse in Tijuana, Mexico to one in an industrial park in the border community of Otay Mesa.

The tunnel is accessed through a 70-foot shaft secured by a cement cover and includes a pulley system on the US side to hoist contraband up into the warehouse.

The second tunnel was about 700 yards long and was more sophisticated, built with a multi-tiered electric rail system and an array of ventilation equipment.

The two tunnels are the sixth and seventh cross-border tunnels discovered in the San Diego area in less than four years, according to authorities.