Crews were at the 9600 block of Quintana Road where an 18-wheeler contained the migrants inside, Fox San Antonio reported. The discovery is part of what is believed to be a human smuggling operation.
Fox News has reached out to the San Antonio Police Department and the Department of Homeland Security.
Authorities have not confirmed the number of dead but Rep. Tony Gonzales, a Republican who represents Texas, tweeted that 42 people died.
“Today in San Antonio it was 102 degrees. Imagine being abandoned inside an 18-wheeler left to die – 42 people died today – will @AliMayorkas even mention their names?” he wrote.
Texas Gov. Greg Abbott put the death on President Biden, who has been criticized for not doing enough to secure the southern border.
“At Least 42 People Found Dead Inside Truck Carrying Migrants In Texas. These deaths are on Biden,” Abbott tweeted Monday evening. “They are a result of his deadly open border policies. They show the deadly consequences of his refusal to enforce the law.”