The highway patrol says the 26-year-old woman, Carol Sanchez of Merced, was stopped by an officer for erratic driving at about 8:30 p.m. Wednesday.
He suspected she was under the influence of alcohol and when he returned to his patrol car the woman ran from the scene.
As she tried to cross lanes of traffic she was hit by a car and pronounced dead at the scene.
The roadway was completely closed in the area for about an hour and traffic was detoured.
All three of the cars involved were taken in for the investigation, and the Fresno area multidisciplinary accident investigation team is helping with the case.
Based on jail records, Merced County sheriff's deputies say Sanchez was booked back in October and December of 2018 for DUI.
Authorities say it's a tragic situation for all those involved, and are still working to determine why the victim decided to run.
Authorities weren't able to determine if there was any alcohol in Sanchez's system.