350 migrants found 'crowded and dehydrated' in trailer in Mexico, authorities say

A vast majority were from Guatemala, according to Mexican authorities.

The discovery was made at dawn after authorities stopped the driver of the trailer at a toll booth in between the cities of Córdoba and Coatzacoalcos in the eastern state of Veracruz, according to a press release from Mexico's National Institute of Migration (INM).

A gamma-ray device detected the presence of people inside the container and authorities heard screams and knocking at the back of the unit. When they opened it, authorities found 350 migrants, including men, women and children, the INM said.

A vast majority of the migrants -- 340 of them -- were from Guatemala while six were from Ecuador, three from Honduras and one from El Salvador, according to the INM.

Meanwhile, the trailer and the driver were taken into custody by the state attorney general's office, according to the INM.