[DJkillos]

Three drug smuggling tunnels equipped with lighting and ventilation — including one with a railcar system — have been
discovered along the U.S.-Mexico border in less than a week, the latest signs that cartels are building sophisticated passages
to escape heightened detection above ground.

Two of the tunnels were incomplete, including one that the Mexican army found in a Tijuana warehouse Thursday with more
than 40 tons of marijuana at the entry. The passage extended nearly 400 yards, including more than 100 yards into the
United States.

Soldiers found the Tijuana warehouse with four moving trucks full of marijuana, a trailer full of dirt, pickaxes, wheelbarrows, drills
and other excavation equipment. The tunnel was equipped with a railcar system.

The Mexican army said three people were detained.

It was the second, major incomplete tunnel discovered in the San Diego-Tijuana area in two days and the third along the U.S.-
Mexico border since Saturday, when a completed passage was found in a vacant strip mall storefront in the southwestern Arizona
city of San Luis.

The 240-yard tunnel in Arizona showed a level of sophistication not typically associated with other crude smuggling passageways
that tie into storm drains in the state.

The tunnel was found beneath a water tank in a storage room and stretched across the border to an ice-plant business in the
Mexican city of San Luis Rio Colorado. It was reinforced with four-by-six beams and lined with plywood.

Investigators believe the tunnel wasn't in operation for long because there was little wear on its floor, and 55-gallon drums
containing extracted dirt hadn't been removed from the property.

Mr. Coleman said investigators can't yet say for sure if the tunnel, estimated to cost $1.5 million to build, was operated by the
powerful Sinaloa cartel. Still, authorities suspect cartel involvement because the group from Sinaloa controls smuggling routes
into Arizona.

It takes six months to a year to build a tunnel, authorities say. Workers use shovels and pickaxes to slowly dig through the soil,
sleeping in buildings where the tunnels begin until the job is done. Sometimes they use pneumatic tools.

The tunnels are concentrated along the border in California and Arizona. San Diego is popular because its clay-like soil is easy to
dig. In Nogales, Ariz., smugglers tap into vast underground drainage canals.

San Diego's Otay Mesa area has the added draw that there are plenty of nondescript warehouses on both sides of the border to
conceal trucks getting loaded with drugs. Its streets hum with semitrailers by day and fall silent on nights and weekends.