U.S. authorities have discovered a 600-yard drug tunnel connecting a warehouse in Tijuana with another on the San Diego side of the border.

U.S. Immigration and Customs Enforcement spokeswoman Lauren Mack said Wednesday that the tunnel had lighting, ventilation and a rail system for sending carts of drugs into the United States and ended at a warehouse in the 9000 block of Via de la Amistad near the Otay Mesa port of entry. Despite the elaborate construction, the tunnel was not as large as other cross-border passageways discovered in recent years and is not big enough for a person to walk through upright, authorities said.

The smuggling operation came to light when agents  with the multi-agency San Diego Tunnel Task Force saw activity around tractor trailer truck parked near the warehouse in Otay Mesa. Agents followed the truck when it left the warehouse, and when it was searched at a traffic checkpoint in Temecula, agents found 10 tons of marijuana, according to the Drug Enforcement Administration. The truck driver and a passenger were arrested.

 Task force members then obtained a federal search warrant for the Otay Mesa warehouse, where they found another 15 tons of marijuana. Mexican authorities found 4 tons of marijuana in the warehouse in Tijuana.

The discovery comes two weeks after the Mexican military in Tijuana seized a record 134 tons of marijuana. That dope was seized in a nearby area of eastern Tijuana, but it's not clear if the two incidents are connected.

Officials have found 125 tunnels since they started recording them in the early 1990s. Of those, 75 have been found in the past four years, most along the California and Arizona border with Mexico.