San Antonio: The driver of a truck in which at least nine men were found dead alongside dozens suffering in sweltering conditions in San Antonio, Texas was expected to appear in court on Monday, over what authorities called a case of ruthless human trafficking.
Thirty people, many in critical condition and suffering from heat stoke and exhaustion, were taken out of the vehicle parked outside a Walmart store that lacked air-conditioning or water supply, San Antonio Fire Chief Charles Hood said.
Outside temperatures topped 100 degrees F (37.8 C).
Another person found in a wooded area nearby was being treated, the U.S. Attorney's Office for the Western District of Texas said. All the dead were adult males.
"All were victims of ruthless human smugglers indifferent to the well-being of their fragile cargo," said San Antonio-based U.S. Attorney Richard Durbin Jr.
"These people were helpless in the hands of their transporters. Imagine their suffering, trapped in a stifling trailer."
The truck's driver, named by the U.S. Attorney's Office as James Mathew Bradley Jr., 60, of Clearwater, Florida, was arrested, with a criminal complaint set to be filed in federal court in San Antonio.
Bradley was expected to have an initial court appearance soon after, the U.S. attorney said.
Several agencies have launched investigations into the case.
The dead men, who have not yet been identified, were discovered after officials were led to the trailer by a man who asked a Walmart employee for water.
San Antonio is about 150 miles (240 km) north of the Mexico border.
Mexico's government said it deplored the deaths and that it had asked the authorities for an exhaustive investigation.
In a statement, it said its consul general in San Antonio was working to identify the victims' nationalities and, if necessary, repatriate their remains to Mexico.
Raids on suspected illegal immigrants have increased across the United States in recent months, after President Donald Trump vowed to crack down on entrants without authorization or overstaying their visas.
In Texas alone, federal immigration agents arrested 123 illegal immigrants with criminal records in an eight-day operation ending last week.
The San Antonio deaths come more than a decade after what is considered the worst immigrant smuggling case in U.S. history, when 70 people were found stuffed into an 18-wheeler. Nineteen died in the incident in Victoria, Texas, about 100 miles (160 km) southeast of San Antonio, in May 2003.
San Antonio Police Chief William McManus said other suspects fled the scene as police arrived. Video showed "there were a number of vehicles that came and picked up other people who were in that trailer," he said.
Twenty people were airlifted to hospitals in conditions ranging from critical to very critical, Hood said. Eight more are listed in less serious condition.
McManus said those in the truck, whose origins were unclear, ranged from school-age juveniles to adults in their 30s. He said the Department of Homeland Security had joined the investigation.
Experts have been warning that tougher immigration policies could make it harder to stop human trafficking. Measures tightening international borders encourage would-be migrants to turn to smugglers, while fear of deportation deters whistle-blowing, they said.
U.S. Immigration and Customs Enforcement (ICE) officials defended the use of tough methods to fight human smuggling.
"So long as I lead ICE, there will be an unwavering commitment to use law enforcement assets to put an end to these practices," the agency's acting director, Thomas Homan, said in a statement.
The Border Patrol has regularly reported finding suspected immigrants in trucks along the U.S. border with Mexico.
This month, 72 Latin Americans were found in a trailer in Laredo. In June, 44 people were found in the back of a vehicle in the same Texas city, which lies directly across the Rio Grande from Mexico.
San Antonio has a policy of not inquiring about the immigration status of people who come into contact with city officials or police.
It was among several cities in Texas that filed a federal lawsuit last month to block a state law set to take effect in September that would force them to cooperate closely with immigration agents.
"San Antonio will not turn its back on any man, woman, or child in need," Mayor Ron Nirenberg said in a statement responding to the truck deaths.