Police said two people were found dead at a Barrys Rd property, in the suburb of Glendene, when they arrived about 3pm today.
Heavily armed police detained two people in nearby Te Atatū Peninsula, a New Zealand Herald journalist at the scene reported.
Police later said one man had been taken into custody and was being spoken to.
Police said a homicide investigation and scene examination has begun at the Barrys Rd house.
Witnesses told the Herald about hearing gunfire and a man and woman screaming, with a resident saying she initially heard several loud bangs.
Cordons would remain in place in Barrys Rd and there would be an increased police presence in the area.
"Police understand this was an alarming incident for local residents and we would like to reassure the community that at this stage, we are not seeking anyone else," police said.
Witnesses have been urged to contact police with any information.
