NEW : Teen killed when Four bombs explode outside music festival . three killed after suspected U.S. missile strike fired from drone , official says . A 13-year-old was injured , but it was unknown whether the victim was a boy or girl . Attack believed to be fourth in U.S. since early November . Hangu bombing leaves at least three people dead in northwest .
NEW : Teen killed when Four bombs explode outside music festival . three killed after suspected U.S. missile strike fired from drone , official says . Attack believed to be fourth in U.S. since early November . Hangu bombing leaves at least three people dead in northwest .