PETALUMA (CBS SF & AP) — The mother of two girls, ages 7 and 9, who were killed last year when the car she was driving crashed and flipped into a Sonoma County river has been arrested in her daughters’ deaths.

The Santa Rosa Press Democrat reported that 27-year-old Alejandra Hernandez will appear in court Tuesday to seek a reduction on her $500,000 bail. Hernandez was arrested Friday and charged with two counts of vehicular manslaughter, felony child endangerment and driving with a suspended license.

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It was unclear exactly what triggered her arrest. Officials would only say that the charges resulted from “the totality of her conduct while driving.”

The fatal crash occurred last August when Hernandez was headed to Rohnert Park to take her daughters, 7-year-old Sayra Gonzalez and 9-year-old Delilah Gonzalez, to school.