SAN ANTONIO — Forty-six people were found dead in and near a tractor-trailer and 16 others were taken to hospitals in an alleged attempt to smuggle migrants to the United States, officials said in San Antonio.

It is one of the deadliest tragedies to claim the lives of thousands of people trying to cross the US border from Mexico in decades. Ten migrants died in 2017 after being trapped inside a truck that was parked at a Walmart in San Antonio. In 2003, 19 migrants were found in a stuffy truck southeast of San Antonio.

A city worker at the scene on a remote side road in southwest San Antonio was alerted to the situation by a call for help shortly before 6 p.m. Monday, Police Chief William McManus said. Officers arrived to find a body on the ground outside the trailer and a partially open trailer door, he said.

Of the 16 people hospitalized with heat-related illnesses, 12 were adults and four were children, Fire Chief Charles Hood said. The patients were warm to the touch and dehydrated, and no water was found in the trailer, he said.

“They were suffering from heat stroke and exhaustion,” Hood said. “It was a refrigerated tractor-trailer, but there was no visible working air conditioning unit on that rig.”

San Antonio Mayor Ron Nirenberg said the 46 who died had “families who were probably trying to find a better life.”

“This is nothing less than a horrific human tragedy,” Nirenberg said.

Those in the trailer were part of an alleged attempt to smuggle migrants into the United States, and the investigation was being conducted by US Homeland Security Investigations, McManus said.

Three people were arrested, but it was unclear if they were absolutely linked to human trafficking, McManus said.

The big rigs emerged as a popular smuggling method in the early 1990s amid an increase in U.S. border enforcement in San Diego and El Paso, Texas, which were then the busiest corridors for illegal crossings.

Before that, people paid small fees to mom-and-pop operators to get them across a largely unpoliced ​​border. As the crossing became exponentially more difficult after the 2001 terrorist attacks in the United States, migrants were driven through more dangerous terrain and paid thousands of dollars more.

Heat is a serious hazard, especially when temperatures can rise dramatically inside vehicles. The weather in the San Antonio area was mostly cloudy on Monday, but temperatures approached 100 degrees.

Some supporters have linked it to the border policies of the Biden administration. Aaron Reichlin-Melnick, director of policy at the American Immigration Council, wrote that he had feared such a tragedy for months.

“With the border closed as tightly as it is today for migrants from Mexico, Guatemala, Honduras and El Salvador, people have been pushed down increasingly dangerous routes. Truck smuggling is up,” he wrote on Twitter.

Stephen Miller, chief architect of former President Donald Trump’s immigration policies, said “human smugglers and traffickers are mean and evil” and that the administration’s approach to security at the borders rewards their actions.

Texas Governor Greg Abbott, a Republican seeking re-election, was candid in a tweet about the Democratic president: “These deaths are on Biden. They are the result of its murderous open border policies.

Migrants – mostly from Mexico, Guatemala, Honduras and El Salvador – have been deported more than 2 million times under a pandemic-era rule in place since March 2020 that denies them a chance to seek asylum but encourages repeat attempts as there are no legal consequences for getting caught. People from other countries, including Cuba, Nicaragua, and Colombia, are less frequently subject to the authority of Title 42 due to higher costs to send them home, strained diplomatic relations, and other considerations.

U.S. Customs and Border Protection reported 557 deaths at the Southwest border in the 12 months ending September 30, more than double the 247 deaths reported the previous year. and the highest since it began tracking in 1998. Most are related to heat exposure.

CBP did not release a death toll for this year, but said Border Patrol conducted 14,278 ‘search and rescue missions’ in a seven-month period through May, topping 12,833 missions. made in the previous 12-month period and more than 5,071 in the previous year.

Read more: What extreme heat does to the human body

– Spagat reported from San Diego. Journalist Terry Wallace contributed from Dallas.

More Must-Have Stories from TIME

contact us at [email protected]