A Sedalia teen was killed in an accident late Friday night in northeast Pettis County.  Investigators said the crash occurred at about 10:15 p.m. near the intersection of Olive Branch Road and Route HH.  The Highway Patrol reports Joshua Holbert, 19, traveled off the side of the road, struck a guardrail, and overturned.  His vehicle continued down an embankment and came to rest in a treeline.  Holbert was pronounced dead at the scene.