Federal authorities are investigating the discovery of a sophisticated 183-foot cross-border tunnel that started inside a home in Mexicali near the U.S.-Mexico border.

The unfinished tunnel extended 3 feet north of the international border wall into Calexico, California, but did not have an exit on the U.S. side of the border, according to Homeland Security Investigations. Authorities announced its discovery Aug. 2.

The 3-by-4-foot shaft — meant to smuggle drugs, people or weapons across the U.S.-Mexico border — had electricity, ventilation, a rail system with a cart, and an electric hoist.

“These types of tunnels enable drug traffickers to conduct illicit activities virtually undetected across the U.S.-Mexico border,” Cardell Morant, special agent in charge of HSI San Diego, said in a statement.

A spokesman for the federal agency said he could not identify which drug trafficking organization dug the tunnel nearly 22 feet beneath the ground. The HSI-led investigation is ongoing with assistance from the El Centro Sector Border Patrol and the federal government of Mexico.

Mexican federal authorities assisted HSI special agents with obtaining access to the Mexicali home where they discovered the entrance to the tunnel, measuring 10 feet by 12 feet.

Last May, Mexican investigators seized illegal marijuana from an unfinished tunnel discovered inside a Tijuana home located across the border from Otay Mesa in San Diego — a preferred spot for tunneling due to the soil consistency and ability to blend in with the busy warehouse district’s traffic.

It was being constructed no more than 50 or so feet from a new National Guard base opened last year, meant to increase security and combat drug trafficking in Tijuana.