Two vehicles parked at a Drouin East residential property were searched through on Sunday morning.
Police said the incident was reported in Beverley St between midnight and 9.30am.
Both vehicles were parked in a carport and left unlocked.
Doors were found ajar and gloveboxes opened. It is not yet known what was stolen.
A vehicle parked in a Yarragon driveway also was targeted on the same night, with a bag containing a wallet and cards stolen.
Parked in a driveway, the vehicle may have accidentally been left unlocked.
Police believe the theft occurred between 9pm on Saturday and 7am on Sunday. The items stolen were valued at $50.