The victim, Concord resident Sherree Lindborg, was walking her dog on Solano Way at Avon Avenue at about 5:40 p.m. when her dog got into the roadway and was apparently hit by a car, Crump said.
Lindborg stepped into the road to tend to her dog and was also hit by a car.
The driver of the car, a 17-year-old boy, stopped and was helping Lindborg when a second car struck her, Crump said.
The driver of the second car stopped briefly, got out of his vehicle and spoke to the 17-year-old, then got back in his car and drove away, Crump said.
The teenager remained at the scene and cooperated with police. Lindborg and her dog both died at the scene, Crump said.
The driver who fled was described as a white man in his 20s. He had brown hair with blond tips and was clean-shaven.
He had a passenger in his vehicle, who was described as a white female with dark, shoulder-length hair.
There was no description of the man's vehicle other than that it was dark in color and possibly a hatchback, Crump said.
Police returned to the scene this morning to document it. Several patches of blood were still on the roadway, marked off with orange spray paint.
Investigators are asking anyone with information about the case to call the Concord Police Department at (925) 671-3220.