Four New York teenagers have been arrested on hate crime charges for throwing rocks at a school bus full of Jewish toddlers, Police said. Police said the three girls and one boy yelled epithets last month as they broke windows on the bus in the Brooklyn neighborhood of Crown Heights. The children were not hurt. The case was part of a string of incidents that have stirred tensions between black and Jewish residents in Crown Heights. The teens were all 14 and are black. The flash points have included an assault on a black college student and an attack on an Orthodox Jewish teen. A race riot erupted in 1991 after a Jewish driver hit and killed a 7-year-old black boy. A 29-year-old Hasidic scholar was stabbed to death in the chaos.