LAREDO, Texas (KGNS) - Six people were found dead Sunday afternoon inside a Union Pacific boxcar in Laredo, Texas.

According to the Laredo Police Department, the bodies were found just after 2:30 p.m. near mile marker 13, near 12100 Jim Young Way, during an inspection at a rail yard.

First responders arrived and confirmed all six had died. Authorities say no one else was found alive inside the railcar.

Investigators have not released the identities of the victims or said how they died.

“At this point it’s a very early phase of the investigation. There’s not a lot to reveal right now because we just began the investigation so far,” Laredo Police spokesperson Joe Baeza said. “What will probably likely proceed from here is an autopsy will probably take place as to determine the cause and manner of the death of the victims in this case, and from there, we’ll go ahead and proceed with other facets of the investigation.”

Officials say temperatures were in the low to mid-90s Sunday afternoon, but they have not said whether heat was a factor.

Union Pacific says it is working with law enforcement as the investigation continues. They released a statement on Sunday:

Union Pacific is saddened by this incident and is working closely with law enforcement to investigate.