An unknown vehicle may be to blame for an accident that injured a Sweet Springs teen Sunday night in Saline County.  According to the highway patrol, Mason Partin, 16, attempted to avoid an oncoming vehicle when he went off of 117th Road and overturned.  Partin’s passenger, Jayson Scarborough, 15, received minor injuries, and refused treatment at the scene.  Authorities have not been able to locate the other vehicle.