A witness has recounted a fatal stabbing in Auckland's Mount Wellington

Cordons remain in place at the Tomuri Place address, where one person died and two people were treated for moderate injuries.

The witness says he saw the incident from his balcony, having noticed a group of four having a drink in the backyard that morning.

He says he's not sure what caused the incident, but he did hear a woman scream for help.

The woman and the alleged attacker then waited on the street for Police to arrive, who detained the man without incident.