Fire investigators have determined that the cause of last week’s building fire at the Humpty Dumpty Kitchen restaurant at 1711 East Main Street in Grass Valley to be accidental.On January 7, 2012 at approximately 8:30 p.m., the Humpty Dumpty Kitchen sustained significant damage from a fast moving fire.  Before being contained, the fire burned from a rear storage area through the ceiling and into concealed space between the first and second floor, as well as into an upstairs office and storage area. The fire investigation began immediately after the fire was brought under control and continued through Friday, January 13, 2012.  As a result of that effort, fire investigators have conclusively determined that the fire was caused by the spontaneous ignition of oily kitchen towels and grill cloths.  All other possible sources of ignition, including electrical,have been systematically ruled out.  These findings have been substantiated by video surveillance equipment recovered from the fire debris and subsequently reconstructed by fire investigators.