Federal agents investigating an underground tunnel near the US-Mexico border that they believe may connect Tijuana to a street in San Diego have said that they uncovered a hidden trafficking operation that allegedly moved more than $45 million worth of cocaine through the passageway. The months-long investigation led to the seizure of more than a ton of cocaine and the arrest of four men accused of using the tunnel to funnel drugs into the United States, according to a June 1 news release from federal prosecutors in Southern California.US-Mexico cross-border tunnel update: $45M in cocaine seized, 4 people arrested (Pexel - representational image)According to authorities, the tunnel connected Tijuana to a business known as "Buy 4 Less" in San Diego's Otay Mesa neighborhood, just north of one of the busiest border crossings in the country. The tunnel was equipped with lighting, ventilation and an electronic transport system.Arrests madeThe release named the defendants as Gregorio Epifanio Hernandez Lopez of San Diego, Brandon Escalante Sandoval of Mexico, Jose Jimenez of San Diego, and Antonio Cortez of Mexico. Lopez is charged with Conspiracy to Use a Cross-Border Tunnel and Conspiracy to Import Controlled Substances, and all of them are charged with Conspiracy to Distribute Controlled Substances.Read More | Massive secret tunnel connecting Tijuana and San Diego uncovered; may have been trafficking center for firearmsA federal complaint said that “investigators from Homeland Security Investigations Tunnel Task Force maintained regular surveillance on the Buy 4 Less warehouse from December 2025 to May 2026 due to suspicious activity there,” per the release.“This investigation and seizure represent a significant blow to the Jalisco New Generation Cartel. The discovery and dismantlement of this sophisticated cross-border tunnel, along with the seizure of more than a ton of cocaine, underscore the commitment and collaboration of Homeland Security Investigations and our Homeland Security Task Force (HSTF) partners” said Kevin Murphy, acting Special Agent in Charge for HSI San Diego. “HSI Special Agents and task force members worked tirelessly to disrupt the flow of dangerous narcotics into our communities, and we remain steadfast in our mission to protect the public and keep our communities safe.”“Law enforcement collaboration is the backbone of dismantling sophisticated transnational drug cartels, as these organizations rely on vast illicit supply chains spanning multiple jurisdictions,” said San Diego County Sheriff Kelly Martinez. “Joint operations disrupt trafficking networks, choke illicit financial flows, and prevent transnational cartels from exploiting jurisdictional gaps. The Sheriff's Office is grateful for the partnerships, hard work, and dedication of everyone involved in this investigation and we will continue to support our federal partners in cases that keep our communities safe.”The tunnel contained operational infrastructure, such as lighting and ventilation systems, investigators said. There was also an electronic sliding mechanism designed to move items in both directions between Mexico and the United States.The shocking tunnel was uncovered through intelligence work conducted by agents with the FGR's Criminal Investigation Agency in coordination with Mexico's Security Cabinet. The search warrant was reportedly executed as part of an investigation into alleged violations of Mexico's firearms and explosives laws, and drug-related offenses too.