At least nine people are unaccounted for hours after the blast , city officials say . A woman tells police her aunt was among the victims killed . A fire in one of the buildings complicates search efforts . At least 3 people were killed in the blast , which leveled two nearby buildings .
At least nine people are unaccounted for hours after the blast , city officials say . A woman tells CNN her aunt was among the victims killed . A sinkhole in front of the buildings complicates search efforts . At least 3 people were killed in the blast , which leveled two apartment buildings .