San Bernardino, California - A woman who went missing after leaving a Christmas gathering with family was located over 200 feet below Highway 18 in a mountainous area north of San Bernardino only after relatives used the Find My iPhone feature to spot her, fire officials said.

The unidentified woman is believed to have crashed sometime overnight after leaving her family's Christmas Day gathering. The accident went unreported for hours, with the woman inside the car and the wreck out of the view of drivers on the highway.

On Monday, San Bernardino County Fire officials said in a Facebook post that her family became concerned when they couldn't get in touch with her the following morning.

Relatives activated the Find My iPhone feature to track her down, eventually leading them to Highway 18, just north of 40th Street, near the San Bernardino community of North Park, fire officials said. Once relatives spotted the vehicle down in the brush, they called 911 for help.

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Paramedic crews responded and reached the vehicle, which was found on its side.

Firefighters used urban search and rescue equipment to raise the woman up to the road, where an ambulance took her to a nearby trauma center.

The woman inside suffered serious injuries, fire officials said. Her condition was not immediately known.