In a reminder of the dangers involved with human smuggling, Customs and Border Protection discovered two Mexican nationals “unconscious and not breathing” attempting to enter the U.S. illegally from Mexico in the trunk of a car, according to reports.

CBP officers found the two men in the trunk of a 2012 Dodge Challenger Tuesday afternoon at the San Ysidro Port of Entry.

According to the LA Times, a CBP officer attempted CPR on the men but was ultimately unsuccessful. The 20-year-old and 28-year-old were ultimately declared dead at local hospitals.

The driver of the vehicle is a U.S. citizen and has been held for questioning.