SAN ANTONIO, Texas (REUTERS) - At least 9 people found inside a sweltering tractor trailer in Texas have died as authorities said they were the victims of "ruthless" human traffickers.
More than 30 people, many in critical condition and suffering from heat stoke and exhaustion, were found in the trailer, which lacked air conditioning or a water supply, San Antonio Fire Chief Charles Hood said. Temperatures outside the vehicle topped 37.8 Celsius.
The truck's driver was arrested and will face charges, said Richard Durbin, US Attorney for the Western District of Texas, and prosecutors are working to identify others responsible.
Eight bodies were discovered after officials were led to the trailer by a man who had approached a Walmart employee and asked for water. Two more people later died en route to hospital, reports said.
"All were victims of ruthless human smugglers indifferent to the well-being of their fragile cargo," Durbin said. "These people were helpless in the hands of their transporters. Imagine their suffering, trapped in a stifling trailer in 100-plus degree heat," he said.
San Antonio is about 240 km north of the border with Mexico. Temperatures in the area held above 37.8 degrees until 6 pm local time on Saturday (July 22) and were expected to soar again on Sunday, forecasters said.
Raids on suspected illegal immigrants have ramped up across the United States in recent months, after President Donald Trump's vow to crack down on those entering the country without authorisation or overstaying their visas.
In Texas alone, federal immigration agents said they arrested 123 illegal immigrants with criminal records in an eight-day operation that ended last week.
The San Antonio deaths come more than a decade after what is considered the worst immigrant smuggling case in US history, when 70 people were found stuffed into an 18-wheeler. Nineteen of them died in the incident in Victoria, Texas, southeast of San Antonio, in May 2003.
San Antonio Police Chief William McManus described the latest fatalities as a "horrible tragedy" and said other suspects had fled the scene as police officers arrived. "Checking the video, there were a number of vehicles that came and picked up other people who were in that trailer,"McManus said.
Twenty people were airlifted to seven hospitals in conditions ranging from "critical to very critical", Hood said. Eight others are hospitalised in less serious condition, he said.
McManus said the people in the truck ranged from school-age juveniles to adults in their 20s and 30s.
He said the Department of Homeland Security had joined the investigation, and that the origin of the truck is unclear.
Experts have warned in recent months that tougher immigration policies could make it more difficult to stop human trafficking. Measures to harden international borders encourage would-be migrants to turn to smugglers and fear of deportation deters whistle-blowing, they said.
US 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 inside trucks along the US border with Mexico. Earlier this month, 72 Latin Americans were found in a trailer in Laredo, it said. In June, 44 people were found in the back of tractor trailer 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 "sanctuary cities" in Texas that filed a federal lawsuit last month to block a new 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.