Temperatures in San Antonio climbed to 101 degrees Fahrenheit (38.3 degrees centigrade) on Monday, while the heat in a packed trailer was likely way higher than that, according to the U.S. National Weather Service.

The bodies of 46 dead migrants were discovered inside a tractor-trailer on Monday in San Antonio, Texas, the city's fire department said, in one of the most deadly recent incidents of human smuggling along the U.S.-Mexico border.