US authorities have found a half-mile tunnel stretching from San Diego to Tijuana that was used to traffic drugs across the Mexican border. Police in the Californian city arrested six people and seized the tons of cocaine and marijuana that were being smuggled through the clandestine passage, which is described as the longest ever to be discovered in the region.

It ran at a depth of 46 feet for 874 yards from an elevator fitted inside the closet of a Tijuana house to a fenced commercial lot in San Diego, where a large trash bin hid its exit. Although its Californian end was "literally a hole in the ground", according to US Attorney Laura Duffy, the rest of the tunnel was quite sophisticated.

"It's a rabbit hole," Duffy told a press conference. "Just the whole way that it comes up and that it comes up out right into the open, it is a bit ingenious, I think, and it's something completely different than what we've seen."

Despite being very narrow − only three feet wide − it was fitted with lighting, ventilation and a rail system used to deliver drugs. "We believe this to be the longest tunnel that we [have] discovered in this district to date," she added.

The discovery was made after Border Patrol agents grew suspicious of heavy traffic around the commercial lot housing the wooden pallet business where the tunnel exited. It was the 13th cross-border passageway found since 2006 in the area known for its relatively easy to dig heavy clay soil.

Monitoring of the site lead to the seizing of thousands of pounds of drugs that had been loaded onto a truck. More marijuana was found inside the tunnel and the trash bin covering its exit. An American citizen, two Cubans and three Mexicans all legally living in the US have been charged with a series of drug-trafficking-related crimes.