At least 46 people have been found dead in a truck on the outskirts of San Antonio, Texas.
A firefighter said 16 people, including four children, were also taken to hospital.
The city of San Antonio, Texas, is a major transit point, 250km from the Mexican border.
Traffickers often use trucks to transport undocumented migrants after encountering them from distant places.
“They had families and they were probably trying to make a good living,” said San Antonio Mayor Ron Nirenberg.
