Six bodies were found inside a train boxcar at a rail yard in Laredo, Texas, after a Union Pacific worker made the discovery near the US–Mexico border.

Authorities confirmed there were no survivors, but the cause of death has not yet been determined and remains under investigation.

Officials said emergency crews responded to the remote loading area, where the rail car is believed to have been used for freight transfers.

Union Pacific is cooperating with law enforcement as investigators work to identify the victims and establish what happened, the New York Post has reported.

The incident comes amid past cases in the region involving migrants found in rail cars or trucks under extreme conditions.