REAR WINDOW SPONTANEOUSLY SHATTERED. DAYLIGHT HOURS, APPROXIMATELY 70 DEGREES FAHRENHEIT, DRY WEATHER CONDITIONS, PARKED IN SHADED AREA. DRIVER WALKED TO VEHICLE, SAT IN DRIVER SEAT, CLOSED DRIVER-SIDE DOOR, AND STARTED VEHICLE UNEVENTFULLY. LESS THAN ONE MINUTE LATER THE REAR WINDOW SPONTANEOUSLY SHATTERED. DRIVER CUT LEFT HAND ON BROKEN GLASS WHEN ATTEMPTING TO RETRIEVE PERSONAL BELONGINGS IN THE REAR COMPARTMENT.