Last Conversations: The families of the six victim...

Six people were found dead on Sunday inside a Union Pacific cargo train in a Texas city along the southern border, officials said.

The bodies were found in a train cargo box in Laredo, Texas, just after 3:30 pm, said Jose Espinoza, a public information officer with the Laredo Police Department.

Laredo lies on the border between Mexico and the US. Union Pacific operates across the border and is the only railroad that services all access points into Mexico, according to the freight company’s website.

Temperatures on Sunday afternoon were in the low-mid 90s, though officials haven’t said how the people died, including whether heat was a factor.

The immigration statuses, genders and ages of the deceased are also not yet known, Espinoza said.

“It’s a very unfortunate event,” Espinoza told CNN. “It was too many lives that were lost.”

Union Pacific said in a statement the company was saddened by the incident and is working closely with law enforcement to investigate.

This is a developing story and will be updated.