HEALDSBURG (CBS SF) — A 77-year-old grandmother was killed and her son and grandson injured in a solo vehicle crash Saturday night on Highway 101 in Healdsburg, according to the California Highway Patrol.

The CHP said officers from the Santa Rosa office were dispatched to investigate a solo vehicle crash along southbound US-101 south of central Healdsburg at 6:57 p.m.

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A preliminary investigation has revealed that an Acura MDX was traveling southbound on 101. For unknown reasons, the vehicle veered to the right onto the shoulder and collided with a guardrail.

The force of the impact caused the Acura to overturn.

The driver, a 40-year-old male from Santa Rosa, was transported to Santa Rosa Memorial Hospital with major injuries.

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Seated in the rear seat was the driver’s 10-year-old son. He was also transported to Santa Rosa Memorial Hospital with minor injuries.

The driver’s 77-year-old mother was seated in the right front seat. Unfortunately, she passed away at the scene.

At this time, the CHP does not believe drugs or alcohol were a factor in the collision.

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Anyone who witnessed the crash or the events leading up to it, is asked to call the Santa Rosa CHP Office at (707)588-1400.