The man was at Middlemore Hospital awaiting surgery.
A hospital spokeswoman said he was in a stable condition.
The sister of the woman who died arrived at the scene about 9.45am from Christchurch.
"I heard the news last night," she said.
"It's very sad."
The woman, who did not want to comment further, was with other family and friends outside the house on Rielly Pl, Mt Wellington.
A handful of police have been at the scene this morning, with a couple doorknocking neighbours and others guarding the entrance to the crime scene.
A post-mortem examination on the dead woman would take place later today and her body remained inside the property.
"Police are not looking for any other persons in connection with the death but have a significant investigation to undertake to ascertain what has occurred at the address," Mr Cahill said.