SAN DIEGO – Three Mexican nationals were found hidden in the cargo area of a vehicle in an alleged smuggling attempt last week at the San Ysidro Port of Entry, U.S. Customs and Border Protection reported.

About 11 a.m. April 1, a 29-year-old man in a Hyundai SUV applied for entry at the border crossing when a CBP border officer spotted a person in the spare tire compartment of the vehicle, the agency said. The driver, a U.S. citizen, was escorted away while officials took the vehicle for further inspection.

Inside the SUV, officers found three men hidden in “a non-factory compartment of the cargo area,” which the agency noted was not easy to get out of without help.

“A person’s life is always in danger when smugglers use specially built compartments to smuggle people across the border,” Sidney Aki, CBP’s San Diego-area director of field operations, said in a news release. “Smugglers will stop at nothing to achieve their goals, even if it means risking human lives.

The men, who were not publicly identified, were ages 29, 24 and 21 with no documents to enter the U.S., according to CBP. They are slated to be returned to Mexico, the agency said.

The SUV also was seized by CBP.