A St. Louis man was severely injured in a one-vehicle crash in Morgan County Saturday afternoon. Daniel O'Reilly, 21, was driving a 2005 Yamaha ATV along a private property road when the ATV struck a ditch, overturned and struck a tree. O'Reilly was thrown from the vehicle. Emergency personnel took O'Reilly to Lake Regional Hospital in Osage Beach for treatment. According to the Missouri State Highway Patrol report, O'Reilly was wearing a safety device at the time of the accident.