BROWNSVILLE, Texas — Members of a task force made up of federal and local authorities found about 50,000 rounds of ammunition beneath the bed of a pickup that was awaiting export to Mexico from Brownsville.

U.S. Immigration and Customs Enforcement says its agents were conducting a routine search for stolen vehicles at a staging area for vehicles being exported from the U.S. Wednesday when a specially trained dog alerted to the 1996 Ford F-150 pickup.

Discrepancies were noted in the truck's bed, where an additional search found an AK-47 assault rifle and .357-caliber revolver. More than a dozen assault rifle magazines were also found.

The U.S. has stepped up outbound inspections at the border in recent years to slow the flow of drug proceeds and weapons that fuel the drug war in Mexico.