AN ANONYMOUS EMERGENCY telephone call yesterday led authorities to halt a train that contained a group of “suffocating” migrants, two of whom were dead, police in Texas said.

The US Border Patrol stopped the train east of Knippa, a small community in southern Texas near the city of San Antonio, police said.

“Approximately 15 migrants were discovered to be in need of immediate medical attention, five of the immigrants were flown out to San Antonio area hospitals, five were transported to area hospitals, and their conditions are unknown,” the statement by the Uvalde Police Department said.

“Two of the immigrants were pronounced deceased.”

Uvalde mayor Don McLaughlin confirmed that two people had died, according to ABC News, but put the total number of people trapped in the container at 17.

Twelve were sent to hospitals, while three were “okay,” McLaughlin said.

Union Pacific, a freight-hauling railroad company, “will lead the investigation”, police said.

Temperatures near where the train was stopped reached 87 degrees Fahrenheit (30 degrees Celsius) in the late afternoon, according to local news channel KSAT in San Antonio.

“We are heartbroken to learn of yet another tragic incident of migrants taking the dangerous journey,” US Secretary of Homeland Security Alejandro Mayorkas said on Twitter.

“We will work with the Uvalde County Sheriff’s Office to hold those (perpetrators) responsible. Smugglers are callous and only care about making a profit,” he added.

Uvalde, where police received the 911 emergency call at 3:50 pm (8.50 pm Irish time), burst into the news 10 months ago with an elementary school shooting in which 19 students and two teachers were killed, along with the gunman.

It was the third-deadliest school shooting in US history after one in 2007 at Virginia Tech and another in 2012 at Sandy Hook Elementary School in Connecticut.