998 Ford Expedition spontaneously catches on fire while parked in apartment complex. It almost burns down a fence and telephone pole. The vehicle was sitting in place for over an hour before the fire occurred. We were sitting in the house when the alarm went off. The fire started on the driver side front. Looked like someone throw something at the tire to start the fire, but firefighters said they were pretty sure it was started in the engine compartment. Anybody have any ideas what it could have been? Go here for pictures.