Auckland's New Windsor is the scene of an armed police operation

The armed offenders squad and Eagle helicopter are carrying out the pre-planned operation on Maioro St, near an off-ramp from State Highway 20.

A witness says they drove past a number of officers who have blocked a "red Dodge" in the middle of the road.

Viveck Pundir said the car was surrounded by police cars on all sides, and an armed officer told the driver, a male, to get out and lie on the ground.

In the early hours of this morning, emergency services were called to an address in Blockhouse Bay Rd.

Police say a man was injured by a firearm, and he was taken to hospital in a serious condition.

Police investigations are ongoing.