TULTEPEC, Mexico — Grieving emergency personnel in the Mexico City suburb of Tultepec carried the caskets of four comrades through the town's streets Friday as authorities investigated whether an attempt to douse burning fireworks with water may have triggered further blasts that killed a total of 24 people.The four were among seven firefighters, police officers and civil defense workers killed when they rushed to the scene of a first blast, only to be felled by three [...]