SAN ANTONIO (AP) — Eight people have been found dead in a tractor-trailer outside a Walmart in Texas in what police are calling a horrific human trafficking case. 
 
 Several other people, possibly dozens, were found in the truck, which didn't have a working air conditioning system, and they were taken to hospitals, firefighters said. 
 
 A person from the truck approached a Walmart employee in a parking lot and asked for water late Saturday night or early Sunday morning, San Antonio police said. The employee gave the person the water and then called police, and when officers arrived they found the eight people dead in the back of the trailer, police Chief William McManus said. 
 
 Investigators checked store surveillance video, which showed vehicles had arrived and picked up other people from the tractor-trailer, police said. 
 
 "We're looking at a human trafficking crime this evening," McManus said. 
 
 He called the case "a horrific tragedy." 
 
 The U.S. Department of Homeland Security was involved in the investigation into what happened, he said. ||||| 8 found dead in trailer at San Antonio Walmart - Homeland Security working with SAPD 
 
 A request for water led to the discovery of eight people dead inside a tractor-trailer at a South Side Walmart parking lot in what police are calling a "horrific tragedy." 
 
 "We're looking at a human-trafficking crime this evening," said San Antonio Police Chief William McManus in a video posted on the department's Facebook page. "Homeland Security is working with us." 
 
 The eight dead are believed to have died as a result of heat exposure/asphyxiation, according to an SAPD press release, but an official cause of death will be determined by the Bexar County Medical Examiner's Office. 
 
 RELATED: U.S. Border Patrol on high alert as 3 bodies of immigrants found in South Texas, heat rises 
 
 Officials said about 30 more people were found inside the truck at 8535 S. Interstate 35 and Highway 16 and transferred to area hospitals for treatment. 
 
 The driver of the truck was immediately detained by police and faces state and federal charges. 
 
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 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. The air conditioning was not working. 
 
 "Our paramedics and firefighters found that each patient had heartrates over about 130 beats per minute and were very hot to the touch," Hood said. 
 
 Police did not know the victims' country of origin, destination, or ages of the deceased or injured, according the press release. 
 
 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. 
 
 READ ALSO: Abandoned on U.S-Mexico border: Photos show life, belongings left behind by immigrants 
 
 The victims included adults and at least two children. The two youngest victims who are among the injured are 15 years old, police said. 
 
 McManus said a check of the video from the store showed that a number of vehicles arrived at the parking lot and picked up a lot of people who were in that trailer who had survived the trip. 
 
 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. 
 
 "San Antonio firefighters and police responded to a horrific scene this morning on the Southwest Side of town. They discovered an alien smuggling venture gone horribly wrong. Eight immigrants were found dead. At least twenty more were in serious condition. All were victims of ruthless human smugglers indifferent to the well-being of their fragile cargo," said Richard L. Durbin Jr., U.S. Attorney for the Western District of Texas. "The South Texas heat is punishing this time of year. These people were helpless in the hands of their transporters. Imagine their suffering, trapped in a stifling trailer in 100-plus degree heat. The driver is in custody and will be charged. We willl work with the Homeland Security Investigations and the local responders to identify those who were responsible for this tragedy." 
 
 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." 
 
 Check back for more on this developing story.
– Eight people have been found dead in a tractor-trailer outside a Walmart in San Antonio, Texas, in what police are calling a horrific human trafficking case. Some 30 other people were found in the truck, which didn't have a working air conditioning system, and they were taken to hospitals, reports CNN. Seventeen of them are in critical condition, while 13 are in serious condition. Authorities said the driver had been held, but they didn't release the driver's identity. A person from the truck approached a Walmart employee in a parking lot and asked for water late Saturday or early Sunday, San Antonio police said. The employee gave the person the water and then called police, reports the AP, and when officers arrived they found the eight people dead in the back of the trailer, police Chief William McManus said. Investigators checked store surveillance video, which showed vehicles had arrived and picked up other people from the tractor-trailer, police said. "We're looking at a human trafficking crime this evening," McManus said. He called the case "a horrific tragedy." The US Department of Homeland Security was involved in the investigation into what happened, he said.