A massive explosion gutted Mexico's biggest fireworks market today and killed at least 31 people and injured 72, say authorities.<br/><br/>The conflagration in the Mexico City suburb of Tultepec set off a quick-fire series of multicolored blasts that sent a vast cloud of smoke billowing over the capital.<br/> <br/>Fire crews struggled for three hours before bringing the blaze under control. Of the 31 confirmed dead, 26 died at the scene and five in hospitals, local media reported Mexico's chief prosecutor Milenio Alejandro Gomez as saying. <br/><br/>The market had been packed with customers buying pyrotechnics for traditional end-of-year festivities. Christmas and New Year parties in many Latin American countries often wrap up with clattering firework blasts.