CONCORD (CBS SF) — A pregnant woman died Tuesday night of injuries suffered in a two-car crash that happened on state Highway 4 earlier that afternoon, California Highway Patrol officials said Wednesday.

The crash happened around 5:40 p.m. on westbound Highway 4 at Port Chicago Highway. A Chevrolet Tahoe collided with a blue Honda Pilot, careened into the center guardrail and flipped twice, according to the CHP.

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The 20-year-old Bay Point woman driving the Tahoe was thrown completely out of the vehicle, and a 29-year-old Oakley man who was a passenger was partially ejected, CHP officials said.

The driver suffered major injuries and was taken to John Muir Medical Center in Walnut Creek. The passenger was taken to John Muir with injuries not thought to be life-threatening, according to the CHP.

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The Tahoe’s driver died at about 8:55 p.m. Neither the driver nor the passenger of the Tahoe was wearing a seat belt, according to the CHP.

The driver of the Honda Pilot, a 37-year-old Hercules woman, wasn’t hurt, though the car sustained minor damage, CHP officials said.

Witnesses told the CHP that the Tahoe was speeding and made an unsafe turning movement, colliding with the Honda Pilot.

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Anyone who witnessed the crash is asked to contact the Contra Costa County-area CHP office at (925) 646-4980.