On Tuesday afternoon, Bexar County District 1 Commissioner Rebeca Clay-Flores shared in a press conference that the medical examiner's office had received 51 bodies. The following day, a county spokesperson confirmed to NBC News that number had increased to 53.
Of the bodies with the medical examiner's office, 40 are men and 13 are women, the spokesperson told the outlet, noting that they had potentially identified 39 of the victims.
"This is the worst human-smuggling event in the United States. This sheds light on how dangerous human smuggling is," Craig Larrabee, the acting special agent in charge of Homeland Security Investigations San Antonio, told CNN in a statement.
As of Tuesday, the victims who were identified hailed from Mexico, Guatemala and Honduras, according to an ICE spokesperson.
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Local officials were first alerted to the presence of the trailer around 6 p.m. Monday, Police Chief Bill McManus told reporters Monday night, reported CNN.
Speaking to reporters on Monday, Fire Chief Charles Hood said 16 survivors of the tragedy (12 adults and four children) had been "hot to the touch" when discovered and "suffering from heat stroke, heat exhaustion."
All 16 were subsequently transferred to hospital, with two people admitted to University Hospital and at least five brought to Baptist Medical Center, PEOPLE confirmed Monday.
"We're not supposed to open up a truck and see stacks of bodies in there," Chief Hood continued. "None of us come to work imagining that."
Local and U.S. authorities revealed Monday that the trailer of the 18-wheeler also had no working water supply or air conditioning.
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Speaking with Good Morning America on Wednesday morning, first responders recalled the horrific scene.
"The heat was torrential," said Chief Hood. "There was no air in that vehicle. There was no water. They suffered. They lost consciousness and then they ended up dying."
Dr. Bryan Everitt, a medical director with the San Antonio Fire Department, said that the victims who survived were "very close" to death.
"They were extremely critical. They needed emergency care," Everitt shared.
Police block the scene where a truck with multiple dead bodies was discovered in San Antonio, Texas
| Credit: Eric Gay/AP/Shutterstock.