A police officer hasa fractured skull, multiple head lacerations and an almost severed finger after what police call a frenzied attack.
The 57-year-old highway patrol officer was set upon with a machete near Taihape at 6.23am on Saturday, after he stopped a stolen car that had been seen driving erratically.
Police say he was attacked from behind as he went back to his car to use its radio. They say the two males inside the stolen car then drove away but were caught when the car crashed shortly after.
Detective Inspector Chris Bensemann says it was a horrendous attack, leaving the officer with major lacerations on his face, on top of his head and at the back of his head.
Mr Bensemann says charges will be laid against an 18-year-old and a 14-year-old, who are likely to appear in court on Sunday.
The red Mazda 323 involved (numberplate NN5654) was stolen in Feilding overnight and police are seeking earlier sightings of it.
The injured officer is in Palmerston North Hospital.
Police Association president Greg O'Connor says the incident confirms again that no officer should be on duty without a firearm.
He says officers - particularly rural ones - need to be able to protect themselves if they're to protect the public.