A member of the public had their car hijacked at gun point after a police pursuit in south Auckland after midday on Sunday.
Police say the incident started with a chase on the Southern Motorway, which was called off due to high speeds.
They say the vehicle exited the motorway at Manurewa and a man got out of the car and pointed a firearm at the following police car.
The offender then forced a nearby driver to take him to an address in Takanini.
Police say a man has been arrested and a firearm and a large amount of ammunition have been recovered.
All trains on the Southern Line were stopped during the police operation but have since resumed.