The South Pasadena, Calif., hardware store thrummed with the usual rhythms of a Wednesday night: customers browsing shelves, cash registers chiming, the low hum of fluorescent lights overhead. Lurking in one of the aisles, a man quietly slipped an incendiary device, made from a cigarette, matches, and paper, into a section displaying foam rubber, with practiced ease. Fire roared to life minutes later, engulfing the store in a furnace of rising panic and confusion.