SAN DIEGO -- A 44-year old Mexican man was arrested Tuesday at the Otay Mesa passenger port of entry in San Diego, Calif., after Border Patrol inspectors said they discovered three Mexican citizens hidden inside the engine compartment of his Ford pickup truck entering the U.S. from Mexico, U.S. Customs and Border Protection officers said.

A woman suffered burns to her right arm, abdominal area, and left leg during the trip, CBP officers said.

After a CBP officer tried treating her, the woman was transported by paramedics to a local medical facility.

Officers said the driver, a Tijuana resident, provided inconsistent answers to their questions, and was asked to pull into a secondary lot for further inspection.

Once there, a narcotics detector dog alerted officers to the hood of the vehicle.

The hood was wired shut, so a crowbar was used to pry it open, officers said.

Once opened, officers said they discovered two women and one man concealed in the engine compartment.

The driver was charged with alien smuggling and transported to the Metropolitan Correctional Center. The vehicle was seized by CBP.