The two officers were part of a covert operation targeting a suspected clandestine methamphetamine lab at a house in Hain Ave, Mangere, when they were disturbed by the occupants.
The officers fled along the street as the armed occupants jumped in a car and pursued them.
One policeman died immediately from a single gun shot and the other was wounded and is being treated in Middlemore Hospital. He will undergo surgery today but his injuries are not thought to be life-threatening.
Police are interviewing two men about the shooting and it is not clear if others are being sought.
Details of the dead policeman, the 28th to die on duty since 1890, had yet to be released by police.
Superintendent Ted Cox, from the Counties Mangere police, said two children, one aged 15 and the other an 11-month old baby, were left in the house.
He said the two shot policemen were part of a police technical support unit and were installing a tracking device on a vehicle outside the suspected P lab house.
"The installation of the device was authorised under warrant from the district court.
"These officers were disturbed by occupants of the house who pursued them while armed, got into a vehicle and chased them down the road.
"As they fled from the address to some 75 metres away where both the officers were shot.
"One unfortunately died immediately from a single gunshot wound. The other is in hospital and will undergo an operation later today. Thankfully, his injuries were not life threatening."
Mr Cox told Radio New Zealand before the shooting there was nothing in the risk assessment of the property to indicate the "people we were targeting or the address indicated a heightened concern".
He said the armed officers squad was not used during the early stages.
He said armed police were nearby to help if needed.
"These offences unfolded very, very quickly and they were unable to respond to save their colleagues."
He said both shot policemen were in plain clothes.
