A 22-year old Hartford woman was struck by a truck and killed on the highway in Newtown yesterday.  State Police say Samantha Figueroa's car broke down in the left lane near Exit 13 eastbound around 3:30am.  She was reportedly standing in the left lane and trying to flag down passing vehicles when she and her car were struck by a Mack truck.  The woman was transported to the hospital where she was pronounced dead.  The highway was closed for more than 6 hours.  State police are asking that any witnesses to the crash contact Trooper Loughman at Troop A in Southbury at 203-267-2200.