Greenwich police are advising residents to keep their guard up after a string of late-night car burglaries.

Police say there have been 30 car break-ins in the last three weeks near King Street and the Merritt Parkway. The thief or thieves have mainly been targeting unlocked vehicles and stealing valuables like cell phones, but authorities say some cases have involved windows being broken as well.

Residents are being advised to park in garages if possible. Police also recommend not leaving valuables in cars and locking car doors at night.

Authorities say they do not have any suspects yet. Anyone with information is advised to contact Greenwich police at 203-622-8000 or 203-622-8021.