Yuma: An incomplete tunnel found stretching from Mexico to Arizona appears to be “the most sophisticated tunnel in U.S. history," authorities said.
The tunnel intended for smuggling ran from a neighbourhood in San Luis Río Colorado, Mexico, to San Luis, Arizona, where it stopped short of reaching the surface.
"It was built in an area that's not conducive to tunnels because of the terrain, and it had a ventilation system, water lines, electrical wiring, a rail system and extensive reinforcement," federal officials said.
Homeland Security Investigations (HSI) started excavating around the tunnel in late July after someone reported a sinkhole near the border wall.
"HSI already had reports of potential tunnel activity in that area and the agency began drilling," according to Angel Ortiz, assistant special agent in charge for Homeland Security Investigations in Yuma.
HSI is a division of U.S. Immigration and Customs Enforcement.
A camera was sent 25 feet (7.6 meters) underground, and the tunnel was discovered on Tuesday. The tunnel measured 3 feet (about 1 meter) wide and 4 feet (1.2 meters) high.
Investigators don't know what exactly the tunnel would have been used for, since it was incomplete. They also don't know how long it had been there, because they don't know what kind of equipment was used to build it.
"If it was done by hand, it would be many months of construction to get as far as it did. But if the builders used heavy machinery it would “potentially a few months, not that long of a period,” Ortiz said.