According to the CHP, the four-month-old child was being carried by her mother as the two walked into oncoming lanes of traffic along northbound Highway 101 in Marin.
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Horrified drivers swerved around the pair to avoid a catastrophic crash, and many passers-by called 911 to report the incident.
One concerned citizen slowed down to try to see if they could help, before the woman attempted to force her way into the passenger side of the vehicle, and the driver sped off.
A nearby Mill Valley Police officer rescued the two individuals by guiding them off the freeway to safety.
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According to the mother, the pair's car broke down on the SR-131 highway onramp, and she decided it would be best to abandon the car and walk on the freeway to get help.
After a thorough DUI investigation, the mother was then arrested on charges of child endangerment and driving under the influence of a drug.