The tragedy, one of the worst in migration in recent years, comes five years after a similar tragedy in the same city, where ten illegal immigrants lost their lives in an overheated trailer.

“We have so far taken care of approximately 46 bodies,” said Charles Hood, the city’s fire chief, during a press conference held at the end of a day when the temperature approached 40°C. .

Sixteen people — twelve adults and four children — were treated and were “conscious” while being transported to nearby hospitals, he said.

“We face a horrific human tragedy tonight,” said San Antonio Mayor Ron Nirenberg. “We hope that those responsible for placing these people in such inhumane conditions will be prosecuted to the fullest extent of the law.”

Trucks such as the one found in San Antonio, a large city in Texas about 240 km from the border with Mexico, are a means of transport frequently used by migrants wishing to enter the United States.

Such a trip is extremely dangerous, especially since these vehicles are rarely air-conditioned and their occupants quickly run out of water.

“The patients we saw were hot to the touch, they were suffering from heat stroke, heat exhaustion, no water was found in the vehicle,” the fire chief said.

– “Call for help” –

The mass grave was discovered by an individual working nearby who “heard a cry for help” and approached to see what was going on, San Antonio Police Chief William McManus said during the press conference.

Three people were arrested, he said, but “we don’t know if they are absolutely connected to this or not”.

The investigation, now federal, has been entrusted to investigators from the Department of Homeland Security, said Mr. McManus.

Some 60 firefighters have been mobilized to take care of the remains and will receive psychological support, said their chief Charles Hood. “You’re not supposed to open a truck and find piles of bodies in there,” he said of the trauma his men faced.

– “Tragedy” –

Mexican Foreign Minister Marcelo Ebrard regretted a “tragedy” on Twitter.

He indicated that the Mexican consul in San Antonio had gone there and had learned that two of the four hospitalized children were of Guatemalan nationality.

The tragedy “was most likely perpetrated by traffickers”, he judged.

Republican Governor of Texas Greg Abbott immediately seized on the tragedy to blame it on Democratic President Joe Biden.

“These deaths are (the responsibility of) Biden. They are the result of his deadly policy of open borders,” he attacked.

The arrivals of illegal migrants increased sharply after the election of Joe Biden, although the latter has been trying since his arrival at the White House to stem the migratory influx by entrusting this thorny file to his vice-president Kamala Harris.

In July 2017, a similar tragedy had marked the spirits: ten migrants had died in an overheated trailer parked in a supermarket parking lot near San Antonio.

At the time, the immigration services indicated that the temperature in the trailer, where dozens of migrants had taken place, could have risen to 65°C.

The driver of the truck, who claimed not to have noticed that he was transporting around 100 people in his trailer, was sentenced in April 2018 to life without the possibility of parole.