San Antonio Police were called to investigate a suspicious semi truck parked in a Walmart parking on Saturday night and discovered numerous dead and injured people inside the trailer.

According to authorities, a total of 38 people were found in the trailer. Eight people were found dead, and at least twenty critically injured, when police arrived. All deaths and injuries were due to the sweltering heat.

A Walmart employee called police for a welfare check after a person from the truck entered the store and begged for water.

“They were very hot to the touch. So these people were in this trailer without any signs of any type of water,” said San Antonio Fire Chief Charles Hood. “It was a mass casualty situation for us.” he added.

Temperatures in San Antonio hit 101 degrees during the day and didn’t drop below 90 degrees until late in the evening. In addition, the trailer’s air conditioning (refrigeration unit) was not working.

“By any standard, the horrific crime uncovered last night ranks as a stark reminder of why human smuggling networks must be pursued, caught and punished,” said ICE director Thomas Homan.

It’s unclear where the truck’s journey began. The driver of the truck was taken into custody and will face federal charges.