"We do have concerns for his safety," Mr Ewers said. "The officers chasing him heard a splash ... they've then seen a person dog-paddling away, but it's dark and wet and they've lost sight of him."
The calamity began when police attempted to stop the driver as he sped along Western Hills Dr near Central Ave at 6.40pm doing 100km/h in a 50km/h zone.
"He's done a U-turn, two passengers have got out - in no particular hurry - and he's taken off and gone up State Highway 14," Mr Ewers said.
The blue Subaru WRX Impreza Saloon then led police on a 50-minute chase along 71km of rural roads. The vehicle was spiked twice before it reached the rest area on Mangakahia Rd. The car was recovered by police with its front tyres entirely worn off.
Police were asking the passengers who hopped out of the car to come forward. One of them was believed to be known to police.
Mr Ewers said it was hoped the man had escaped the river and in this case, there may also be someone in the Parakao area that had assisted him.
Police were appealing for any information about the man. Contact Whangarei Police on 09 430 4500 or Crimestoppers on 0800 555 111.