The pedestrian attempted to get out of the travel lanes but was struck by a van before she could clear the lane.
The dark colored passenger car left the scene and continued eastbound on the South Marietta Parkway, Baldwin said. The van remained on scene, and the driver spoke to emergency responders.
No charges are pending at this time against the van driver. Police are looking for the driver of the passenger car.
The name of the pedestrian is currently being withheld.
The pedestrian was transported to Kennestone Hospital with serious injuries.