The bodies of 46 migrants were discovered inside a tractor-trailer in San Antonio, Texas on Tuesday, city officials said, in one of the deadliest cases of human smuggling along the U.S.-Mexico border in recent memory.

An officer with the San Antonio Fire Department stated that they discovered "stacks of bodies" and no traces of water in the truck, which was discovered adjacent to train tracks in a secluded area south of the city.

The agency stated that no children were among the dead, despite the fact that 16 other people found inside the trailer were taken to hospitals for heat stroke and dehydration, including four minors.

Monday's peak temperature in San Antonio, some 250 kilometers (160 miles) from the Mexican border, reached 103 degrees Fahrenheit (39.4 degrees Celsius) with heavy humidity.

"The victims we encountered were quite hot to the touch, suffering from heat stroke and fatigue," San Antonio Fire Chief Charles Hood stated during a news conference.

It was a refrigerated tractor-trailer, yet there was no observable airconditioning unit on the vehicle, Hood said.

The deaths once again show the difficulty of controlling the record-breaking numbers of migrants crossing the U.S.-Mexico border.

William McManus, the city's police chief, stated that a nearby building employee heard a call for assistance and came out to investigate. The worker discovered the trailer's half open doors and, when inspecting the interior, discovered a number of lifeless bodies.

According to McManus, this is the largest occurrence of its kind in the city, and three persons have been detained, although their role is unknown.

A representative for U.S. Immigration and Customs Enforcement (ICE) stated that its Homeland Security Investigations division was investigating "an alleged incident of people smuggling" in conjunction with local law enforcement.

The issue has been challenging for U.S. President Joe Biden, a Democrat who took office in January 2021 promising to overturn parts of Donald Trump's restrictive immigration policies. 

Republicans have questioned Biden's border strategy prior to November's midterm congressional elections.

On Twitter, Mexico's Foreign Minister Marcelo Ebrard referred to the migrants' suffocation in the truck as a "tragedy in Texas" and stated that consular personnel will travel to the hospitals where the victims had been transported to assist "anyway feasible."

A spokesman for the Honduran foreign ministry said that the event would be investigated by the country's consulates in Houston and Dallas. 

Ebrard said that two Guatemalans were hospitalized, and Guatemala's foreign ministry announced on Twitter that consular personnel were en route to the hospital "to confirm if there are two Guatemalan youngsters there and their condition."