Police are searching for four men in Providence who allegedly threatened a victim over a pack of cigarettes.  Police were called Monday to the area of Manton Avenue after Margarito Bermudez-Alvarez reported being robbed by a group with a shotgun.  Bermudez-Alvarez was crossing the street when a group of men in a car pulled up next to him and demanded cigarettes.  The suspects are all believed to be in their 30s, driving a car with tinted windows and no plates.  An investigation is ongoing.