Mexico City: Mexican authorities found 129 migrants packed into the back of a cargo truck, the National Institute of Migration said on Saturday.
The "migrants from Guatemala, Honduras, El Salvador and India" were discovered on Friday night in the eastern state of Veracruz, it said in a statement.
Mexico is in the middle of a heat wave that has killed at least eight people.
The truck full of migrants was found in the town of Sayula de Aleman, where temperatures are forecast to hit 44 degrees Celsius (111 degrees Fahrenheit) on Sunday, according to the National Meteorological Service.
The migration institute said 51 migrants from Guatemala were returned to that country.
Another 19 unaccompanied minors from Guatemala and Honduras were transferred to a special shelter and the rest were transferred to a migration station.
Thousands of migrants, many fleeing poverty and violence in their own countries, cross Mexico daily hoping to reach the United States.
Along the way they often fall victim to organized crime gangs or human traffickers.
More than 2,100 migrants were abducted in Mexico last year, according to the National Institute of Migration.
