A statement from the National Security Commission on Thursday said police officers spotted the truck on a highway in the northern border state of Nuevo Leon and observed that the driver and a passenger were not wearing seatbelts.
They pulled the vehicle over, detected noises and signs of movement from the cargo area and ordered the driver to open it.
Nearly all of the 113 migrants packed inside inside were from Central America. They also included two Ecuadorians and a Nepalese national. The commission said none of them were legally in the country.
The driver and passenger were arrested, and the migrants were delivered to immigration authorities.