(CNN) The passageway that zigzagged underground between San Diego and Tijuana, Mexico, was so sophisticated that officials call it a "super tunnel."
The drug tunnel stretched the length of nearly six football fields and had lighting, ventilation and an electric rail system, authorities said Thursday.
It was 35 feet deep, 4 feet tall and 3 feet wide. And it was built by one of Mexico's most notorious criminal organizations, the Sinaloa cartel, U.S. Attorney Laura Duffy told reporters.
And now three people are in custody and could face federal charges after investigators seized more than 8 tons of marijuana and 325 pounds of cocaine linked to the tunnel, U.S. Immigration and Customs Enforcement said in a statement.
Word of the detentions comes a day after investigators shut down what they described as the newly completed and "highly sophisticated" tunnel, which connected a warehouse in Mexico with another warehouse in a California industrial park.
Duffy said that authorities have a message for cartels tied to drug tunnels.
"If you continue to build and attempt to use these tunnels, we are determined to make this a big waste of your dirty money," she said. "Not only will we take your drugs and shut down your tunnels before you even get an opportunity to use them, but we're now in a position where we're going after your management."
Prosecutors are reviewing charges against the detained individuals and expect they will be filed later Thursday, according to Duffy.
The discovery was made by the San Diego Tunnel Task Force, which includes members of ICE, U.S. Customs and Border Protection and the Drug Enforcement Administration.
Authorities compared the find to other "super tunnels" discovered along the border in recent years.
"It was just two years ago, November 2011, that we discovered and shut down two elaborate super tunnels like the one here today," Duffy said. "And at the time we did so, we stood before you and we warned the cartels directly. If you build them, we're going find them, and if we find them, we're going to destroy them. Today, we again make good on that promise."
The Sinaloa cartel, named after the Mexican state where the gang was formed, is one of the most powerful drug-trafficking groups in the nation.
Leader Joaquin "El Chapo" Guzman's nickname, which means "shorty," matches his 5-foot-6-inch frame, though he has climbed to great heights in the drug smuggling business. Forbes magazine has estimated that "El Chapo" is worth $1 billion.
The U.S. Treasury Department has declared him the most influential trafficker in the world, and Mexican authorities have been on his tail since his 2001 escape from a Mexican prison in a laundry cart.
Officials said the drugs seized as part of this week's tunnel investigation had an estimated street value of nearly $12 million.