A police officer was bashed from behind while making an arrest at what police have called a "large gathering of anti-social road users" just outside Palmerston North last night.
Officers were called at around 1am to Works Rd at Longburn, with somebody having been hit by a vehicle.
They were met by a "volatile situation".
While one police officer was arresting a person for disorderly behaviour, he was struck on the head from behind and knocked to the ground, Detective Sergeant David Wilson said.