Initial investigation indicates woman may have tried to overtake another vehicle when her car collided with bus.
Aya Litrat killed along with sons Dror, 3, and Itamar 14 months, when their car hit a bus near Ashkelon.
Investigators rule out an electrical short as the cause of the blaze.
Two suffer serious injuries; Rescue services use crane to evacuate eight-story residential building.
Family say were treated with disrespect by police while filing complaint; victim found dead in Ramat Aviv.