A 3,500-acre fire in the juncture of the San Bernadino and San Gabriel mountain ranges of southern California leapt onto a busy freeway Friday, sending motorists scrambling from their cars, destroying multiple houses, and forcing the town of Baldy Mesa to evacuate. The fire jumped up onto I-15 near Cajon Pass suddenly on Friday, forcing drivers on the main connector between Los Angeles and Las Vegas to abandon their vehicles and retreat up a nearby hill.