Officials say the exact cause of a North Carolina beach house fire that killed seven college students is undetermined. But improperly discarded smoking materials cannot be ruled out.

• 官方声称引起卡罗莱纳州北部的海滩房屋大火的具体原因还未确定，这场大火中有7名大学生死亡，不排除是不当的可燃物的随意丢弃引起的。