UPDATE, 1:20 p.m.: Three people were in the car, not four as previously reported, a CHP official tells KHUM DJ Bayley Brown. One of the three has been transported to Redwood Memorial Hospital.

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UPDATE, 12:24 p.m.: One person in the car has multiple lacerations and possibly a cracked rib, dispatchers say. Another is believed to be trapped between a seat and a car door, and is unable to extricate himself or herself.

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UPDATE, 12:20 p.m.: Emergency personnel are having trouble finding the vehicle, which apparently went over a bank. Dispatchers have the victims on the line. They say they are unable to get up to the road to flag down their rescuers. 

A dispatcher is asking fire engines to turn on their sirens, hoping that the crash victims hear the engines as they approach, and that dispatch can bring the parties together that way.

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A vehicle traveling on Highway 101 near Myers Flat overturned a few minutes ago, and first reports indicate that four people are trapped inside.

The vehicle is not blocking the roadway. 

Emergency personnel are en route. Updates from CHP dispatch below.