THE VEHICLE WAS STATIONARY AT IDLE FOR APPROXIMATELY 15 MINUTES. FIRE STARTED UNDER THE HOOD AT UNKNOWN LOCATION. INITIAL SMELL OF "SOMETHING HOT" WAS FOLLOWED BY SMOKE THROUGH VENTS. NOTICED SMOKE BETWEEN HOOD AND WINDSHIELD. PAINT ON HOOD BUBBLED IN APPROXIMATE LOCATION ABOVE OIL CAP / DIESEL PARTICULATE FILTER. SHUT ENGINE OFF AND EXITED THE VEHICLE.