Washington DC - A federal grand jury has indicted 11 people for allegedly orchestrating a migrant smuggling operation that ended in the deaths of seven people traveling in a freight car, the Justice Department announced Friday.

From at least April 2023 through May of this year, the defendants allegedly smuggled undocumented migrants into the US aboard freight trains, charging between $1,500 and $10,000 per crossing, the agency said in a statement.

In the early hours of May 9, the smugglers allegedly loaded at least seven migrants into a Union Pacific freight railcar in Del Rio, Texas, on the US-Mexico border.

The railcar had no ventilation, while outside temperatures topped 88 degrees Fahrenheit.

The train departed for San Antonio, where the smugglers reopened the railcar and found the migrants in distress, including one who was already dead.

The smugglers then allegedly left the body near the railroad track and fled, while the train continued on its journey.

"On May 10, a worker at the Union Pacific Rail Yard in Laredo saw a leg sticking out from a Conex shipping container," the Justice Department statement read. "Upon inspection, six aliens were discovered deceased in the shipping container."

Another migrant was found dead along the railroad tracks in San Antonio.

Of the seven victims, who included a 14-year-old, four were Mexican nationals, and three were Honduran.

One defendant, Mayra Alekandra Huerta, was arrested shortly after the Del Rio tragedy, while eight others were taken into custody in Texas last week. Two remain at large.

Fatal smuggling incidents are a recurring feature of undocumented migration along the US-Mexico border.

In 2022, 53 migrants died after they were abandoned inside a tractor-trailer in sweltering heat on a remote road in Texas.