According to information from DPS, a white Toyota Avalon was traveling in the westbound lane when it slowed down as the car was approaching a construction zone on Highway 239 just west of Choate near the intersection of Highway 239 and County Road 128.
An eighteen-wheeler traveling behind the car crashed into the rear of the car, killing the two women seated in the rear seat and seriously injuring the two men in the front of the car.
The crash caused the truck, driven by Dan Tucker, 59, of Runge, to flip onto its side, partially blocking part of the highway. Tucker was not seriously injured in the crash.
The flat-bed truck belonged to Tri-C Ventures, of Runge and was loaded with farm seed out for delivery.
The driver of the white Toyota Avalon, Gary Deskin, 65, of Karnes City, and the front seat passenger, John Ray Harris, 72, were both airlifted by helicopter to University Hospital in San Antonio.
The two women in the rear seat of the car, Margaret Hensley, 59, and Carol Harris, 69,were pronounced dead at the scene by Karnes County Justice of the Peace Precinct 1 Kathy Stewart.
Police said all four passengers in the car were local Karnes County residents.
Karnes County Sheriff's Office personnel responded to the scene as well as DPS, Karnes County EMS, Karnes City Fire Department and Rescue 1 who worked to extricate injured passengers from the car.
Police say the accident remains under investigation.
More information on this story will be posted online as it becomes available.