Mexican authorities found 175 migrants, mostly from Guatemala, crammed into a truck in Chiapas State, the National Migration Institute (INM) announced.

Service agents heard screams and banging from inside the trailer when they stopped it at a checkpoint in this southern Mexican state. The driver refused to open the back door of the truck, but the faces of the migrants could be seen through the ventilation slots.

Photos released by the INM show people standing side by side inside the lorry, before they begin to disembark one by one with the help of Institute workers.

Most of the immigrants came from Guatemala. But there were also many from El Salvador and Honduras, one from the Dominican Republic and one from Pakistan. The group included 28 unaccompanied minors from Guatemala and two from El Salvador.

Would-be immigrants fleeing poverty and violence in Latin American countries often pay smugglers to smuggle them through Mexico and into the US. Earlier this year, a group of around 300 people were spotted inside a truck in the eastern Mexican state of Veracruz.

Although the U.S. says the number of migrants attempting to cross the border from Mexico has dropped by 70 percent in recent weeks, the number of those planning to reach the U.S. through the dangerous jungle between Panama and Colombia has launched.