At least 46 people have been found dead in an abandoned truck on the outskirts of San Antonio, Texas, a state in the US, according to the BBC.
The abandoned truck was found by emergency responders on Monday after the report of a dead body around the scene.
According to the BBC, San Antonio, which is 250km (150 miles) from the US-Mexican border, is a major transit route for people-smugglers.
Emergency responders have taken 16 people, including four children, to hospital.
The survivors were said to be “hot to the touch” and suffering from heat stroke and heat exhaustion.
Charles Hood, San Antonio fire chief, told reporters that the abandoned truck had no working air conditioning or point for drinking water.
“We’re not supposed to open up a truck and see stacks of bodies in there. None of us come to work imagining that,” he said.
The victims were suspected to have died from exhaustion and dehydration as San Antonio’s climate is blisteringly hot in the summer months, with temperatures reaching 39.4C (103F) on Monday.
Reacting to the incident, Marcelo Ebrand, Mexico’s foreign minister, said two Guatemalans were among those taken to hospital and that the nationalities of the other victims were not immediately clear.
Three people have been arrested in connection with the incident and the investigation has been handed over to federal agents.