Incident marks one of the deadliest tragedies involving people attempting to cross US border from Mexico in recent decades

• Full report: At least 46 people found dead in Texas trailer truck

Forty-six people were found dead in a sweltering tractor-trailer that was abandoned on a remote back road in San Antonio, Texas shortly before 6pm local time (12am GMT) on Monday.

Sixteen people were taken to hospital, including four children, and treated for heat stroke and exhaustion.

A San Antonio fire department official said they found “stacks of bodies” and no signs of water in the truck. “The patients that we saw were hot to the touch, they were suffering from heat stroke, exhaustion,” the San Antonio fire chief, Charles Hood, told a news conference. “It was a refrigerated tractor-trailer but there was no visible working A/C unit on that rig.”

A city worker heard a cry for help from the truck and discovered the gruesome scene, the police chief, William McManus, said.

A spokesperson for US Immigration and Customs Enforcement (Ice) said that its Homeland Security Investigations division was investigating “an alleged human smuggling event” in coordination with local police.

San Antonio mayor Ron Nirenberg said the 46 who died had “families who were likely trying to find a better life … This is nothing short of a horrific human tragedy.'”

Texas governor Greg Abbott, a Republican running for reelection, said in a tweet: “These deaths are on Biden. They are a result of his deadly open border policies.”

Mexico’s foreign minister, Marcelo Ebrard, called the suffocation of the people in the truck the “tragedy in Texas” on Twitter and said consular officials would go to the hospitals where victims had been taken to help “however possible”.

A spokesman for the Honduran foreign ministry told Reuters the country’s consulates in Houston and Dallas would be investigating the incident. Ebrard said two Guatemalans were sent to hospital and Guatemala’s foreign ministry said on Twitter that consular officials were going to the hospital “to verify if there are two Guatemalan minors there and what condition they are in”.

The incident is among the deadliest tragedies to have claimed thousands of lives of people attempting to cross the US border from Mexico in recent decades. Ten migrants died in 2017 after being trapped inside a truck that was parked at a Walmart in San Antonio.

South Texas has long been the busiest area for border crossings. People ride in vehicles though border patrol checkpoints to San Antonio, the closest major city, from which point they disperse across the United States.