At least 50 migrants were found dead in the back of a tractor trailer in San Antonio on Monday, federal law enforcement officials confirmed to CBS News on Tuesday. Sixteen others — 12 adults and four children — were taken to local hospitals with heat-related injuries.
The federal officials confirmed to CBS News Homeland Security and Justice reporter Nicole Sganga this appears to be the deadliest human smuggling case in modern U.S. history.
On Tuesday morning, Mexican Foreign Relations Secretary Marcelo Ebrard said on Twitter, citing U.S. authorities, that the victims included 22 Mexicans, 7 Guatemalans and two Hondurans. Investigators are still determining the nationalities of those who died or were hospitalized, Sganga reports.
Three individuals believed to be part of the suspected smuggling conspiracy are being detained by the federal agency Homeland Security Investigations, a spokesperson with U.S. Immigration and Customs Enforcement, or ICE, told CBS News immigration reporter Camilo Montoya-Galvez.
Police Chief William McManus said at a press conference Monday that authorities received a call at approximately 5:50 p.m. local time from a worker who had heard cries for help and found the trailer with its doors partially open. The worker found a number of dead bodies inside the trailer, McManus said.
San Antonio Fire Chief Charles Hood said the 16 people taken to the hospital were all conscious when they were found, though they were "weak" and would have been unable to leave the trailer on their own. He said all were "hot to the touch" and suffering from heat-related injuries like heat exhaustion and heat stroke.
He said there were no signs of water or a working air conditioner in the truck, and authorities said it's not clear how long the group was in the truck before they were found.
The victims were a mix of men and women and varied in age, but none of the deceased appeared to be minors, officials said.
Hood said first responders were being debriefed to help them process what they witnessed.
"You're not supposed to open up a truck and see stacks of bodies in there," he said. "None of us come to work imagining that."
San Antonio Mayor Ron Nirenberg called the situation "a horrific human tragedy."
Homeland Security Investigations is leading the investigation into the incident and will work in conjunction with the San Antonio Police Department, law enforcement officials told CBS News.
DHS said in a statement it is "horrified at this tragic loss of life near San Antonio. This speaks to the desperation of migrants who would put their lives in the hands of callous human smugglers who show no regard for human life."
An ICE spokesperson said in a statement that Homeland Security Investigations responded to the scene after receiving a call from the police department. The spokesperson said more details will be released as the investigation continues.
More than 20 emergency vehicles responded to the scene, CBS affiliate KENS-TV reported.