A driver suffered life-threatening injuries in a single-vehicle crash on County Road 209 in Clay County on Tuesday afternoon, according to the Clay County Sheriff's Office.
The driver, whose identity was not immediately released, was flown to a hospital.
Deputies said the car ran off the road and into a culvert for unknown reasons.
County Road 209, also known as Russell Road, in the cross-street area of Watkins Road near Green Cove Springs was closed in both directions.
Deputies said drivers should expect a lengthy road closure in the area and take alternate routes.
This story will be updated as more information becomes available.