SAN DIEGO (AP) — Federal authorities say they've discovered a tunnel between Mexico and San Diego — possibly one of the secret passages drug cartels have dug to move dope into the United States.

U.S. Immigration and Customs Enforcement officials announced the discovery of the tunnel on Thursday.

Thy aren't releasing any details. However, such cross-border tunnels have been linked in the past to drug smuggling.

Mexican authorities said an investigation is underway in the Aeropuerto neighborhood west of Tijuana International Airport and near the Otay Mesa neighborhood of San Diego.

In April, authorities found a half-mile-long tunnel between the two cities and seized tons of cocaine and marijuana.

It was the 13th secret passage found along California's border with Mexico since 2006.

U.S. Immigration and Customs Enforcement issued the following statement:

U.S. Immigration and Customs Enforcement's (ICE) Homeland Security Investigations (HSI) Tunnel Task Force is confirming the discovery of a cross-border tunnel in the San Diego/Tijuana Border area. In order to ensure the integrity of the ongoing investigation and the safety of those involved, HSI San Diego is not providing additional details at this time. Additional information will be provided as soon as it is appropriate to do so.