Police are investigating a possible connection between multiple car break-ins in three southwestern Connecticut communities.Police report five cars break-ins in two Darien fitness centers Wednesday. Those break-ins follow car thefts in Norwalk and Fairfield on Monday and Tuesday. Police are calling the car robberies ?smash and grab crimes? where thieves smash the car windows and grab valuables inside.Norwalk police have made one arrest in connection with the thefts from unlocked cars on Regency Drive and Murray Street. Darien and Fairfield have not reported any suspects. Police advise all southwestern Connecticut residents to be cautious about locking their car and keeping valuables out of view.