NATIONAL CITY, Calif. — The discovery of over 5,000 pounds of meth inside two trucks in National City is believed to be one of the largest seizures of the drug in San Diego County, the U.S. Attorney’s Office said Friday.

Around 5 p.m. Thursday, a 20-foot box truck crossed into the United States through the Otay Mesa Commercial Port of Entry, the U.S. Attorney’s Office said in a news release. Law enforcement observed the truck traveling to Hoover Avenue and 30th Street in National City, where agents saw several men unloading dozens of cardboard boxes from the truck and placing them in a Dodge van, the release said.

Agents discovered about 148 bundles of a substance that tested positive for methamphetamine and weighed more than 5,000 pounds, according to the U.S. Attorney’s Office.

Agents apprehended four men: Rafael Alzua, 37, Mario Contreras, 41, Ethgar Velazquez, 44, and Galdrino Contreras, 41. All four men are Tijuana residents.

The men were charged Friday with conspiracy to distribute methamphetamine and if convicted, face 10 years to life in prison, plus a $10 million fine.