Police discovered a full-size yellow school bus that had been converted into an oven, complete with smokestack, exhaust fans and working fire, after a neighbor said he smelled smoke. The bus, in the backyard of a residence owned by a Hasidic Jewish congregation, was turning out flat, round loaves of unleavened matzo bread for the Jewish Passover holidays, which begins next Monday at sundown, said Sgt. Lou Scorziello of the Spring Valley police. He said police found the bus bakery early Friday morning. "It was up and running," he said. "Smoke was coming from the stack and there was a working fire." He said the fire was fueled by gas from lines illegally extended from the house. None of the necessary permits had been obtained.