(EAGLE PASS, Texas.) — A desperate 911 call made from a freight train led Texas authorities to 12 migrants trapped inside a stifling boxcar, including one who was pronounced dead at the scene and three others in need of hospitalization, officials said.

The discovery was made on Saturday afternoon near Eagle Pass, Texas, on the U.S.-Mexico border and came a day after 17 migrants were found locked in a “suffocating” train freight container in Uvalde County, including two who perished, authorities said.

Saturday’s incident unfolded about 4:30 p.m. at a Union Pacific rail yard, when someone from inside a boxcar parked at the yard called 911, a Union Pacific spokesperson said.

One migrant was pronounced dead at the scene. Three other migrants were taken to a Fort Duncan Regional Medical Center in Eagle Pass for treatment, according to the Eagle Pass Fire Department.

Union Pacific said it contacted the U.S. Border Patrol, which detained the eight additional survivors.

The U.S. Department of Homeland Security has launched a human smuggling investigation. No arrests have been announced.

The Mexican Consulate of Eagle Pass released statement, saying it was aware of the incident. The migrant who died in the episode was an adult Mexican national, according to the consulate.

The others migrants rescued were from Ecuador, Mexico, Honduras, and Colombia, the consulate said.

The incident came a day after 17 migrants were discovered in a Union Pacific freight train container near Knippa, Texas, in Uvalde County, including two men who died, according to a statement from the Uvalde Police Department

Police were notified by an unidentified third-party caller that there were numerous migrants trapped inside the “suffocating” container. The U.S. Border Patrol was to able to get the train stopped alongside Highway 90 near Knippa and discovered the migrants, authorities said.

The Texas Department of Public Safety and the Department of Homeland Security are investigating the incident.

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