Ledyard — State and Ledyard police on Monday were investigating another convenience store robbery — the fourth robbery or attempted robbery in the region in less than a week and at least the fifth in the last month.

Monday’s robbery occurred at 8:30 p.m. at the Henny Penny on Route 12 in the Gales Ferry section of Ledyard. Details of the incident and a description were not available late Monday.

Police from several surrounding towns were already discussing similarities between the suspects in a spree of robberies that include stores in Montville, Groton, New London and Stonington.

State police detectives are investigating the March 22 robbery at the Chucky's Mobil on Route 32 in Montville. The suspect in that robbery displayed a handgun and was wearing a black hooded sweatshirt and what appear to be white gloves.

On Thursday, a white man wearing a hood, sunglasses and yellow gloves entered the Henny Penny on Route 12 in Groton and made off with cash after displaying a handgun to the store clerk.

Shortly before 8 p.m. on Saturday, a white, unshaven male with yellow gloves, a dark hooded sweatshirt and sunglasses attempted an armed robbery at the Sunoco gas station at 715 Colman St. in New London. The man did not obtain any cash, according to police.

About an hour after the attempted robbery in New London, Stonington police said a white male wearing a black sweatshirt robbed the Henny Penny at 2 Roosevelt Ave. in Mystic.

Waterford police are investigating a robbery Monday afternoon at the Charter Oak Federal Credit Union on Boston Post Road. Police have released few details about the description of the suspect in that case.