CHP officers say 42-year-old Heather Martinez was driving on Highway 180 near Piedra when she pulled over off the road around 2:30 Sunday morning.
That's when she got out of her car and walked into lanes of traffic and was hit by 32-year-old Kenia Rodriguez, authorities said.
Authorities say Rodriguez stopped momentarily but then kept driving down the highway.
Officers eventually caught up to her and found she was under the influence.
Detectives are still investigating why the victim walked onto the road.