Update 8:30 p.m.:
Thomas Homan, acting director of Immigration and Customs Enforcement, told the Associate Press Sunday the group of people found in the semi Sunday were only a third of the original passengers.
"Based on initial interviews with survivors of the weekend tragedy, more than 100 people may have been packed into the back of the 18-wheeler at some point in its journey," Homan said.
The U.S. Attorney’s Office for the Western District of Texas, identified the driver of the truck as James Mathew Bradley Jr., 60. Bradley is currently in federal custody and facing both state and federal charges.
San Antonio police found 38 people packed into a windowless, sweltering cargo trailer in a southwest side Walmart parking lot early Sunday morning. Most of the occupants were in their 20s and 30s — but some passengers were as young as 15. Eight men in the group had already died from severe heat exposure before San Antonio Police Department officers discovered the abandoned semi truck. Another passenger died in the hospital later that day.
“They were very hot to the touch,” said San Antonio Fire Department Chief Charles Hood at a 3 a.m. press briefing. “So these people were in that trailer without any signs of any type of water, so you’re looking at a lot of heatstroke, a lot of dehydration.”
Around 20 of the passengers were taken directly to local hospitals in “extremely severe” or critical condition, Hood said.
A spokesperson from U.S. Customs and Border Protection said the group was likely made up of immigrants who crossed over the Mexico border on foot and were being transported further north by human traffickers. It's unclear how long the truck had been parked in the middle of the lot.
Walmart staff only noticed the truck after one of its passengers stopped and asked an employee for water early Sunday. After giving them water, they employee called SAPD.
At the morning press briefing, SAPD Chief William McManus called the scene a "horrific tragedy" — but said it's far from unexpected.
“This is not an isolated incident; this happens quite frequently," he told reporters. "Fortunately, we came across this one. Fortunately, you know, there are people who survived.”
The driver of the semi, who has yet to be identified, has been arrested and will face criminal charges.
Discovered during a period of particularly heated debate over undocumented immigration in the U.S., many are saying the incident is an example of why current immigration policies are in need of reform.
"This morning’s events are a harsh reminder that the language of 'border security,' 'national security,' and collaboration between local police and ICE does not make us safer or more secure," wrote RAICES in a Sunday press release. The immigrant advocacy group is holding a 6 p.m. memorial service Sunday at San Fernando Cathedral for the men who died in the trailer.
“The tragic event...shines a bright light on the plight of immigrants looking for a better life and victims of human trafficking," said San Antonio Mayor Ron Nirenberg in a statement Sunday. "Our response should serve as a lesson to the world that San Antonio will not turn its back on any man, woman or child in need.”