EL PASO, Texas (Border Report) – A southbound operation at the Presidio, Texas, port of entry netted federal officials $465,755 in undeclared cash this week. The seized currency was in 14 bundles in a wall behind the vehicle’s restroom; the two bus drivers were arrested, according to U.S. Customs and Border Protection.

The seizure took place at noon on Tuesday after CBP and Homeland Security Investigations agents selected a passenger bus headed to Mexico. A CBP dog trained to sniff out guns and currency alerted the agents to an anomaly, and the bus was passed through an X-ray system.

The walled compartment held the 14 currency-filled bundles, CBP said.

HSI arrested and took custody of the drivers – two Mexican citizens ages 47 and 68 – questioned and released six bus passengers. The bus was seized as well.

“The majority of CBP’s work involves the processing of people and items entering the U.S. from abroad however CBP also routinely conducts operations to stop the flow of unreported currency, weapons, ammunition and other items from leaving the U.S.,” CBP El Paso Director of Field Operations Hector Mancha said in a statement.

Although there is no limit to the amount of money that travelers may carry when crossing U.S. borders, federal law [31 U.S.C. 5316] requires that travelers report currency or monetary instruments in excess of $10,000 to a CBP officer at the airport, seaport, or land border crossing when entering or leaving the United States.

Penalties may include seizure of most or all of the traveler’s currency, and potential criminal charges. An individual may petition for the return of seized currency, but the petitioner must prove that the source and intended use of the currency is legitimate.