6 people found dead inside a boxcar in Texas, officials say

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

The bodies were found in a Union Pacific train at a rail yard in Laredo, around 160 miles south of San Antonio, just after 3:30 p.m. local time, said Jose Espinoza, a public information officer with the Laredo Police Department.

The circumstances of their deaths are unknown, said Laredo police spokesperson Joe Baeza, and an investigation is underway.

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 in Laredo were in the low-mid 90s, though it’s unclear whether heat was a factor.

The immigration status and ages of the deceased are not yet known.