Police say that 15 reports of thefts from cars in Hartlepool were made last night.
One man aged in his twenties has now been arrested on suspicion of theft from a motor vehicle.
He remains in police custody.
During March, officers say there were 159 victims of theft from vehicles across the town.
CCTV enquiries have shown suspects trying vehicle door handles in an attempt to find anything which has been left insecure.
Officers have carried out a number of arrests in connection with the offences and some have since appeared in court.
Inspector Mal Suggitt, from Hartlepool Neighbourhood Team, said: “The majority of the incidents we have seen involve suspects simply trying door handles until they find vehicles that have been left open.
“Items such as keys to other vehicles, BB guns, credit cards, sports items, laptops, iPads and wallets containing hundreds of pounds in cash have been stolen.
“I would urge the residents of Hartlepool to keep their vehicles secure and not to leave valuables in their vehicles.”
Anyone with information regarding the incidents is asked to contact Cleveland Police on 101.