A spike in car crime on Kingswood, Hull, is being investigated by police.
Tom-toms and mobile phones have been stolen in a total of 16 vehicle-related offences reported in the area in March.
Sergeant Andy Crawforth, of the local policing team, said such crimes were rare on Kingswood.
He said: "This type of offence is very unusual for the area.
"Opportunist thieves tend to look for premises and vehicles that have been left unlocked, which has been the case for some of the reports we're investigating.
"Criminals want to steal high-value items in just a few seconds, so if a car, van, house or garage is insecure, they try their luck to earn a fast buck.
"My advice is to keep all valuables out of sight, clear marks left by navigation devices from the window, buy a steering or handbrake lock.
"Lock the vehicle at all times, even if left alone for a few seconds, and try to park in a well lit area."
Officers are delivering information to residents in Chevening Park, Budworth Park, Elvaston, Knightly Way and Aldenham Park, and would like to hear of any incidents that have not been reported.
Anyone with information is asked to call police on 101.
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