Six people were found dead on Sunday afternoon in a train’s boxcar in Laredo, Texas, a spokesman for the Laredo Police Department said.

At approximately 3 p.m. local time, a person responsible for loading and unloading the train cars before they headed north reported the discovery of the bodies.

The police and fire departments later confirmed the deaths, said the spokesman, Investigator Joe E. Baeza.

The circumstances of their deaths were unknown, he said. The police are investigating.

This is a developing story. Check back for updates.