Police have discovered the bodies of eight people and 17 others in critical conditions at a Walmart Parking Lot in San Antonio, Texas, early Sunday.

Officials were called to the scene when an employee was approached by a fleeing victim, who was asking for water.

In what has been described as a "human trafficking crime,"' police and emergency officials, claim the people found in a trailer parked at the Wal Mart parking lot-- suffered heat stroke due to 'sweltering' conditions.

Police: Truck driver arrested

San Antonio police chief, William McManus is calling this a "horrific tragedy." McManus also confirmed a driver had been held, but the identity hasn't been released.

The eight fatalities and dozens of injured were found inside a truck, that authorities say, 'lost its air conditioning' and subsequently had suffered severe heat stroke.

Most of the victims were in their early 20's and 30's, and two of the dead were young children, officials claim. Temperatures reached over 100 degrees Saturday in San Antonio, and never fell below 90, according to local weather services.

According to police, investigator checked surveillance video, and it showed cars approaching the truck picking up people from the trailer.

Fire Chief: Victims were 'hot to the touch.'

"They were very hot to the touch. So these people were in this trailer without any signs of any water," Fire Chief, Charlie Hood, described in the video to reporters on social media.

Hood told reporters, "it was a mass casualty for us." As horrific this crime scene was, Hood noted to reporters Sunday, which could have been far worse due to the weather element.

"We are very fortunate that there weren't 38 people who were locked inside of this vehicle dead,"

Those who survived all had accelerated heartbeats, according to Hood

According to reports, the Department of Homeland Security is also assisting the investigation due to the severity of the crime.

Authorities still haven't discovered where the truck originally came from.

2003 Human Trafficking Crime

Back in May of 2003, 19 immigrants died as they were being transported from Southern Texas to Houston. According to the prosecutors, the truck driver of that vehicle could hear the victims in the back begging for water but refused to free them, leading to their deaths.

The driver of the truck was re-sentenced in 2011, is serving 34 years in prison. More details are awaited on the incident.