Border Patrol agents apprehended a Mexican man over the weekend who had attempted to smuggle a Chinese national into the U.S. by hiding him in his pickup truck's gas tank.

U.S. Customs and Border Protection confirmed Monday that agents in Calexico, Calif., discovered a man who had been concealed in a specially built compartment of a Ford F-150's gas tank, located beneath the bed of the truck.

According to the border patrol agency, around 7 a.m. Friday, a 41-year-old male Mexican citizen drove through the East port of the Calexico checkpoint. An inspection officer said the driver appeared nervous and asked him to step outside the vehicle for further questioning and inspection.

Agents used an X-ray imaging system to scan the truck. The test found that there was a large object in the base of the bed. While searching the gas tank, they discovered it had been divided into two parts. One side contained enough fuel to make the cross-border trip and the other held a man.

The driver was arrested and will face federal charges. The 31-year-old Chinese man was put on an immigration hold and will go through removal proceedings following his criminal proceedings.

The agency has not revealed how the 31-year-old Chinese man traveled to Mexico or worked with smugglers to get to the U.S. The incident comes as Republican nominee Donald Trump has warned that terrorists could travel to Mexico and cross into America by way of the southern border.