Emergency personnel responded shortly after 4:30 a.m. Monday to a vehicle rollover crash on Route 3 southbound just south of FF Road between Columbia and Waterloo.
The vehicle, a 2008 Ford utility, came to rest on its roof.
There were two occupants in the vehicle, with one woman being transported by ambulance to Mercy Hospital South in St. Louis County. Both occupants were wearing their seat belts, police said.
The roadway was cleared at 5:20 a.m.