They wanted to speak to the driver of a black flat-deck truck which was seen travelling north towards Luggate around the time of the incident.
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The truck was described as having an empty deck with a hiab crane at the back.
"If you saw a black truck on the Luggate-Cromwell Road around 3-4pm on
Friday, police would also like to hear from you.
"Witnesses or anyone with dash camera footage that can assist the investigation are asked to contact police on 105 quoting file number 191130/9827.
Meanwhile, an Auckland woman experienced a close shave with a flying axe after it smashed through her windscreen near Dargaville in October.
The woman walked away with only bruises and cuts after the incident and both the driver of the vehicle and a child inside the car were uninjured.
The vehicle the woman was in was travelling towards Dargaville when another vehicle passed going the other way.
Elsewhere, a woman's vehicle was struck by a projectile of a high-powered firearm while driving along the Northwestern Motorway in Auckland on November 22.
Police did not believe the woman, who was shot in the face, was "specifically targeted" but wouldn't say where she was shot from.
The woman had been driving towards the city and passing under the Royal Rd overbridge around 9.40am when the projectile went through her windscreen.
The woman was taken to Auckland City Hospital with serious injuries but later became stable. Police said the injuries were not life-threatening.