PHOENIX, Ariz. -

A California woman has been arrested after allegedly abducting her infant granddaughter, who was later found unharmed in Arizona.

Maricopa County Sheriff's officials say 57-year-old Carolyn Ruth Ferguson of Huntington Beach was located Wednesday night along with the 6-month-old girl at a gasoline station in Tonopah, west of Phoenix.

Ferguson told authorities that her car had broken down.

Authorities in Huntington Beach had issued an Amber Alert for the girl Wednesday afternoon. The baby's mother alleges that Ferguson took the child while she was asleep at her home in Hemet.

The girl's relatives say Ferguson is bipolar and hasn't been taken her medication.

Ferguson had her court initial appearance Thursday suspicion of child abuse, custodial interference and endangerment.

Her bond was set at $50,000. She doesn't have a lawyer yet.