DOUGLAS, Ariz. — Federal authorities arrested two Mexican nationals who were carrying over $100,000 in unreported U.S. currency when they attempted to cross back into Mexico.

U.S. Customs and Border Protection officers at the Port of Douglas were conducting outbound inspections on Tuesday when a Chevrolet truck driven by Dennis Armando Brown-Lopez, 43,  and Maria Delia Barrientos-Romero, 45,  tried to cross into Mexico. Officers found the money hidden in the truck.

Officers seize illegal cash by the millions each year. In the fiscal year of 2014, which ended on Sept. 30, officers seized $3.1 million at Arizona ports. They seized $6.5 million in the fiscal year prior to that one.

Brown-Lopez and Barrientos-Romero were referred to the U.S. Immigration and Customs Enforcement's Homeland Security Investigations.