Vandals smashing car windows in central Nelson are believed to be doing so in drive-by attacks.
In a post on their Facebook page, Nelson police say they believe the offender or offenders are hitting the cars while in another vehicle.
The number of reported incidents is steadily increasing, with Sergeant Craig Barker saying the total is now up to 51.
Glazier Francis Lagrutta, of Nelson Auto Glass, said he had seen a dramatic increase in the number of cars coming in with windows broken by vandals.
Mr Lagrutta said the vandalism seemed to be occurring most frequently in the Waimea Rd, Britannia Heights and Quebec Rd areas.
Nothing was being stolen from the cars, so he suspected it was "just fun and games" for whoever was behind the attacks.
"They're hitting people who can't afford it."
Mr Lagrutta said a lot of the broken windows looked like they had a bullet hole in them, leading him to believe that "it's a bunch of twits with a BB gun".
Nelson police said they did not believe a gun was involved. It was more likely that a blunt instrument was used.
Mr Barker said police did not yet have a description of any suspects or their vehicles. He urged members of the public with information about the vandalism to come forward.
Anyone with information or who wants to report damage to their car can call Nelson police on 546 3840.
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