A window washer attacked a driver with a cleaning brush after the motorist refused to let him wash his windscreen.
The incident in Auckland's Greenlane last night comes amid simmering tensions between frustrated motorists and increasingly intimidating window washers.
Police are now warning motorists not to pay window washers and to stay in their vehicles if approached.
Officers were called to the corner of Great South Rd and Greenlane West at 10.30pm on Wednesday.
Police said a man waiting in his car at the lights had refused to let the window washers wash his windscreen.
The man got out of his car and was then allegedly hit over the head with a window cleaning brush. The window washer and two others in his group fled.
One was caught by police while the other two were found during a wider search of the area a short time later.
Police said one of the men was found with property allegedly stolen during a burglary of a house on Great South Rd the night before.
The attack victim was taken to hospital and was treated for a wound to his head.
He was released from hospital early this morning.
Police said a 17-year-old Takanini man has been charged with burglary and assault with a weapon. The two other men were later released by police.
Inspector Andy King said window washers would continue if motorists kept paying them.
"Window washers are intimidating and we are continuing to work with Auckland Council to stop them," he said.
"There is some practical advice we can give to motorists which we hope will lead to a reduction in their attempts; don't engage with them at all if possible and don't pay them. If they're making money they will keep doing it."
Police receive frequent calls about window washers at locations across greater Auckland, ranging from intimidating behaviour to the risk they cause traffic by darting around moving cars.
Police have recently started arranging for service stations to have window washing brushes marked or engraved. When the marked brushes are found in the possession of window washers, officers will look to charge them with theft or receiving stolen property.
Continuous patrols around the affected intersections are ongoing, and where possible, police will try to move the window washers on. Window washers under the age of 17 will be returned home or to school.
Auckland Council has the power to prosecute window washers under the Public Safety and Nuisance Bylaw, which makes it an offence to wash windows at intersections in an unsafe and intimidating manner.
It has pursued prosecution, or is in the process of pursuing prosecution, in 71 cases, with a total of 132 charges for breach of the bylaw.
Mr King said police and the council were continuing to work together to identify offenders and prosecute them under the bylaw.
"This is an ongoing challenge for us and we are putting a lot of work into stopping window washers, however in the meantime we ask the public to help us by making it not worth their while, don't pay them and don't engage with them."