San Antonio police officer
A San Antonio police officer removes crime scene tape from near the area where eight people were found dead in a tractor-trailer loaded with multiple others, outside a Walmart store in stifling summer heat in what police are calling a horrific human trafficking case, Sunday, July 23, 2017, in San Antonio.
Nine immigrants have died after they were trapped inside a tractor-trailer at a Walmart parking lot, officials confirmed Sunday afternoon. Several people are still in critical condition at local hospitals.

Eight immigrants were found dead inside the closed trailer just after midnight Saturday. More than two dozen others, the only ones left of the estimated 100 who started the trip, were taken to area hospitals, many in serious to critical condition due to the heat.

An initial report that two more people had died was the result of hospital error, according to Homeland Security, who asserted that just one more person had died, putting the death toll at nine. All the victims so far are adult males, officials said.

Law enforcement is at the scene where people were discovered inside a tractor trailer in a Walmart parking lot at IH35 South and Palo Alto Road, Sunday, July 23, 2017. Reports say that 8 were dead including two children and several were transported to area hospitals. Seventeen were with life threatening injuries.

The driver of the vehicle, 60-year-old James M. Bradley Jr. of Florida, was booked into a federal jail in San Antonio on Sunday morning for his alleged role in what U.S. Attorney Richard Durbin called "an alien smuggling venture gone horribly wrong."

The truck was parked at a back corner of the Walmart parking lot at 8538 S. Interstate 35 and Texas 16 on the Southwest Side at least since Saturday evening. The eight immigrants are believed to have died as a result of heat exposure/asphyxiation, according to a San Antonio Police Department news release, but an official cause of death will be determined by the Bexar County Medical Examiner's Office. No names or ages have been released of any of the 10 victims.Officials said it was a refrigerated trailer but the air conditioning wasn't working. Experts estimate the temperature inside the closed-in trailer could have reached dangerous levels; at just 80 degrees outside, the temperature inside a closed vehicle can reach 115 degrees in a half hour, according to the National Weather Service. San Antonio reached Saturday's high of 100 degree at 6 p.m.

San Antonio Police Chief William McManus said police were alerted by a Walmart employee who was approached by someone in the truck who asked the employee for water.

"These people were in the trailer without any water," said San Antonio Fire Chief Charles Hood "Looking at a lot of heat stroke, a lot of dehydration."

Engine 25 arrived at 12:26 a.m., Hood said, and firefighters started extricating patients out of the back of a semi-truck.

"Our paramedics and firefighters found that each patient had heart rates over about 130 beats per minute and were very hot to the touch," Hood said.

Police did not know all of the victims' countries of origin, destination or ages, although officers said the two youngest victims are 15.

University Hospital and SAMMC received 17 people with life-threatening injuries, police said, and 13 victims were taken to five other area hospitals with non-life threatening injuries.

Five men and one woman were taken to University Hospital in critical condition, presenting heat exhaustion.

While it is not known how long the tractor-trailer had been in the parking lot, the temperature inside the truck would have climbed rapidly, said Jason Runyen, meteorologist for the National Weather Service.

"Most of the heating that would occur once someone is inside of a vehicle that doesn't have AC would occur in the first 30 minutes of them being in there," Runyen said.

McManus said a check of the video from the store showed that a number of vehicles arrived at the parking lot Saturday evening and picked up people from the trailer.

The black, red and white truck had a logo of Pyle Transportation on it.

Mike Pyle and Tom Colton of the company said Bradley is an owner-operator who owns his own semi but is authorized to haul under the Pyle name.

"It's our trailer, but it's his truck," Pyle said.

Bradley was not authorized to be hauling anything in Texas when the immigrants were discovered, Pyle and Colton said.

Both Pyle and Colton said they were shocked by the news of the deaths.

"This is terrible," Pyle said in reference to the victims.

Around 6:30 a.m. Sunday, the tractor-trailer was still parked adjacent to Walmart, along with a hearse, with several police cars positioned nearby. A large portion of the parking lot remained cordoned off by police tape as detectives gathered evidence.

Around 7 a.m. Sunday, SAPD's Eagle helicopter arrived on scene, repeatedly circling over the Walmart parking lot and the adjacent wooded area for around 20 minutes. Police said in an earlier news conference that they conducted a sweep of the woods to search for any potential victims who may have escaped the tractor trailer, and that they would conduct a secondary sweep at daylight.

The tractor-trailer was towed from the scene

Around 10 a.m., the tractor-trailer was towed from the scene. A few police cars remained, guarding a small area still cordoned off by police tape.

Throughout the morning, several onlookers stop to examine the scene, taking pictures and commenting on the horrific deaths.

Border Patrol agents in Laredo have reported an increase in smuggling attempts in tractor-trailers in recent weeks, starting with the discovery of 44 people from Mexico and Guatemala discovered after police stopped an 18-wheeler on June 19 near one of the city's international bridges.

On July 7, agents found 72 people from Mexico, Ecuador, Guatemala and El Salvador inside a locked trailer in the same part of town. The next day, they found 33 people from Mexico and Guatemala inside a trailer stopped at the Border Patrol checkpoint on Interstate 35. In another incident last week, agents at the checkpoint found 16 people inside a locked trailer, according to a news release from Border Patrol.

"These criminal organizations view these individuals as mere commodities without regard for their safety," Laredo Sector Assistant Chief Patrol Agent Gabriel Acosta said in a statement released last week. "The blatant disregard for human life will not be tolerated. We will continue to work with our law enforcement partners to disrupt and dismantle these organizations and prosecute those responsible."

In one of the biggest smuggling tragedies in the country's history, 19 people died in 2003 after being abandoned in a trailer in Victoria. The driver of the truck was sentenced to life in prison, but that was overturned and he was later given a prison term of nearly 34 years.

Thomas Homan, U.S. Immigration and Customs Enforcement acting director, said as long as he leads the agency, "there will be an unwavering commitment to use law enforcement assets to put an end" to smuggling.

"By any standard, the horrific crime uncovered last night ranks as a stark reminder of why human smuggling networks must be pursued, caught and punished. U.S. Immigration and Customs Enforcement's Homeland Security Investigations works year-round to identify, dismantle, and disrupt the transnational criminal networks that smuggle people into and throughout the United States," Homan said. "These networks have repeatedly shown a reckless disregard for those they smuggle, as last night's case demonstrates. I personally worked on a tragic tractor-trailer case in Victoria, Texas, in 2003 in which 19 people were killed as a result of the smugglers' total indifference to the safety of those smuggled and to the law."

Staff writers Nicole Bautista and Jason Buch contributed to this story.