NEW : Teen killed when three bombs exploded outside a festival . One killed after suspected U.S. missile strike fired from drone , official statement . Attack believed to be fourth in Pakistan since early November . Mosque bombing leaves at least five people dead in northwest .
NEW : Teen killed when three bombs explode outside music festival . Four killed after suspected U.S. missile strike fired from drone , official says . Attack believed to be fourth in Pakistan since early November . Mosque bombing leaves at least three people dead in northwest .