Six people were found dead Sunday afternoon inside a Union Pacific cargo train boxcar near a Laredo, Texas, rail yard, according to local authorities. The discovery was made after a Union Pacific employee called police around 3 p.m. to report multiple casualties inside the car, the Laredo Police Department said.

First responders confirmed that all six, five men and one woman, had died. According to the Webb County Medical Examiner’s Office, two victims have been identified: a 29-year-old woman from Mexico and a 24-year-old man from Honduras. The medical examiner stated that the woman died of hyperthermia, or heat stroke, and it is considered likely that heat was the cause of death for the others, though final examinations are pending. The deaths occurred as temperatures in Laredo reached the low to mid-90s on Sunday.

Dr. Corinne Stern, the Webb County Medical Examiner, said, "I believe that the remaining individuals probably all succumbed to heat stroke as well, but their exams are not completed at this time, so I will not rule on their cause and manner yet."

One of the male victims appears to be a teenager, but his identity has not been confirmed yet. The agency believes the victims originated from Mexico and Honduras, although ongoing identification efforts include fingerprint analysis and checking cellphones for data.

Authorities have not released information about the train’s origin or whether this incident involved a smuggling operation. Laredo Police spokesperson Jose Baeza described the rail yard as several miles long, comparing it to a seaport for trains. He told reporters, "This is where they load and unload a lot of rail cars," and noted the investigation is still in its early stages.

Union Pacific stated it is "saddened by this incident" and is working closely with law enforcement. Laredo, which borders Mexico, is a major land port of entry. Authorities are cooperating with consulates to notify families and continue to investigate the circumstances surrounding the deaths.