Two women were killed and four people were hurt Wednesday morning in a wreck in Douglas County that witnesses said happened when a tractor-trailer allegedly ran a red light.

A tractor-trailer northbound on Thornton Road, south of I-20, struck the driver's side of a Nissan Sentra, sending both vehicles into the southbound lanes around 11:30 a.m., according to the Georgia State Patrol.

As the Nissan was pushed into the southbound lane, it struck two additional vehicles, according to the GSP.

The passenger in the Nissan, Tracy P. Downer, 44, of Atlanta, died at the scene, according to Gordy Wright with the GSP. The driver, Michelle Kamika Chinnis, 35, of Smyrna, died after being extricated from the vehicle, Wright said.

Four people in the vehicles struck on the southbound side of Thornton Road were transported to Grady Memorial Hospital, where they were later listed in stable condition, Wright said.

The tractor-trailer driver, 64-year-old Robert John Sansom, of Colorado, was not injured, according to troopers.

Witnesses told Channel 2 Action News that the truck ran a red light.

"The crash remains under investigation by the GSP Specialized Collision Reconstruction Team and the Georgia State Patrol post in Villa Rica," the GSP said in an emailed statement Wednesday evening. "Any charges from the crash will be pending the completion of the investigation."