California Highway Patrol press release: 

On April 17, 2015, at approximately 5:35 PM, Trevor Stevens of Blocksburg, CA was driving a 2013 Toyota Tacoma north on US 101, just north of SR 162.  For reasons still under investigation, Stevens made an unsafe turning movement to the right and his Toyota left the roadway, collided with a tree and overturned.  As a results of the collision Stevens suffered major injuries and was transported from the scene for medical treatment.  Stevens was wearing his safety belt at the time of the collision.  Alcohol impairment does appear to be a factor in this collision.