(CNN)At least 46 people were found dead Monday in sweltering conditions in a semitruck in San Antonio, according to authorities, in a scene the mayor called a “horrific human tragedy.”
The victims were migrants, City Councilwoman Adriana Rocha Garcia said Monday after a briefing by the San Antonio police chief. Their discovery comes as US federal authorities have launched an “unprecedented” operation to disrupt human smuggling networks amid an influx of migrants at the US-Mexico border.”An alleged human smuggling event” was alerted by San Antonio police to the US Department of Homeland Security’s investigation unit, which is leading the probe, an Immigration and Customs Enforcement spokesperson said Monday. The incident appears to be among the most deadly in recent years for migrants near the southern border.Three people are in police custody, though their connection to the situation is unclear, Police Chief Bill McManus said at a news conference Monday night.Migrant rescues along US-Mexico border climb amid sweltering heat and high water levelsAuthorities were alerted to the scene just before 6 p.m., when a worker in a nearby building heard a cry for help, McManus said. The worker found a trailer with doors partially opened and saw people deceased inside, McManus said. Read MoreSixteen people — 12 adults and four children — were taken to medical facilities, San Antonio Fire Chief Charles Hood said. Three taken to Methodist Hospital Metropolitan were in stable condition, a Methodist Healthcare spokesperson said.Those found alive were hot to the touch and suffering from heat stroke and exhaustion, Hood said, and were conscious when taken for care. There was no sign of water in the refrigerated semitractor-trailer and no visible working air conditioning unit, he said. High temperatures Monday in the San Antonio area ranged from the high 90s to low 100s, according to the National Weather Service. Victims ‘were likely trying to find a better life'”I am heartbroken by the tragic loss of life today and am praying for those still fighting for their lives,” Homeland Security Secretary Alejandro Mayorkas said on social media. “Far too many lives have been lost as individuals — including families, women, and children — take this dangerous journey.” The 60 firefighters that were on scene are being put through a critical incident stress debriefing, Hood said. “We’re not supposed to open up a truck and see stacks of bodies in there. None of us come to work imagining that,” the fire chief said. “It’s tragic,” Mayor Ron Nirenberg said Monday. “There are, that we know of, 46 individuals who are no longer with us, who had families, who were likely trying to find a better life. And we have 16 folks who are fighting for their lives in the hospital.”First on CNN: Biden administration launches 'unprecedented' operation to disrupt human smuggling as caravan moves northAssistance to Mexican nationals would be provided, Mexico’s consul general in San Antonio said on social media. At least two of the 16 survivors have been identified as Guatemalan, according to Mexico’s foreign minister, citing the consul. US officials are working to better handle the flow of migrants to the US-Mexico border, Mayorkas told CNN earlier this month. Their operation builds on previous initiatives to go after smugglers whom migrants often depend on as they make their way to the border. Homeland Security last spring also announced an effort to crack down on criminal smuggling organizations, alongside federal partners.Migrants in recent years have faced other tragedies and challenges enduring dangerous heat and terrain while trying to cross the US-Mexico.Rescues across the US southern border have outpaced those of the last fiscal year. Since October, more than 14,000 searches and rescues have happened along the US southern border, according to US Customs and Border Protection — including rescues from dangerous water crossings. That’s up from 12,833 searches and rescues in fiscal year 2021, with more than three months left to go.In 2017, 10 people died and dozens were injured from heat-related conditions after being discovered in a tractor-trailer at a San Antonio Walmart. The driver of the truck was sentenced to life without parole in a federal prison.In 2003, 18 victims ranging from age 7 to 91 were found dead in the back of a semitruck with about 100 other people as temperatures soared past 100 degrees, investigators said. The driver in that case was initially sentenced to life in prison, but in 2011 was resentenced to almost 34 years in prison. Heat has not been the only danger to migrants crammed in vehicles. In March 2021, a semitruck packed with 25 people collided with an SUV on an isolated stretch of California’s Imperial Valley, killing 13 undocumented immigrants.