46 migrants found dead in back of truck in San Antonio

46 migrants were found dead inside the truck, many of whom have been admitted to hospital

The bodies of 46 immigrants who died inside a tractor-trailer were found Monday in San Antonio, Texas, according to city officials, one of the worst recent incidents of human trafficking across the U.S.-Mexico border.

Sixteen people, including four children, were taken to hospital, a fire official said.

"The patients we saw were hot to the touch, they experienced heat stroke and fatigue," San Antonio Fire Chief Charles Hood told a news conference. "It's a refrigerated heavy vehicle, but there's no noticeable A / C unit in that equipment."

San Antonio, 250 km (150 miles) from the US-Mexico border, is a major transit route for smugglers.

Human traffickers often use trucks to transport undocumented immigrants after entering the United States and meeting them in remote areas.

San Antonio Fire Chief Charles Hood told reporters after emergency responders initially responded to reports of a dead body around 18:00 (23:00 GMT) local time.

Mexico's Foreign Minister Marcelo Ebrard said two of those taken to the hospital were Guatemalans nationals. It was not immediately clear what country the other victims belonged to.

The city's Police Chief William McManus said an individual who works in a close-by building heard a sob for help and emerged to research. The specialist found the trailer entryways to some extent opened and peered inside and tracked down various dead bodies.

McManus said it was the largest such incident in the city and that three people were in custody following the incident and their connection was not yet clear.

A spokesman for the U.S. Immigration and Customs Enforcement (ICE) said its Homeland Security intelligence unit was working with local police to investigate a "human trafficking incident."

Jack Staten, a former senior official at ICE's intelligence unit, says the I - 35 highway near the site of the trucks passes through the Mexican border via San Antonio and is a popular hijacking route due to heavy truck traffic. 

Staten said immigrants from the 2017 incident continue to be intercepted in the area. "It was a while before such a tragedy happened again," he said.