South Norfolk Police are warning vehicle owners to be vigilant after a spate of thefts last week.
Thefts from vehicles overnight on November 23 and 24 occurred in Taylor Road, Buxton Road and Roydon Road in Diss.
Police said tools, cash, documentation, and a sat-nav were among the items stolen.
Some of the vehicles are believed to have been left insecure when the incidents took place.
South Norfolk Police have said that owners should remove all valuables when vehicles are left unattended and ensure their vehicles are locked.