Fire and Emergency New Zealand said it received reports of a well-involved house fire in Freshney Place shortly before 7am.
Hato Hone St John said one person was taken to Middlemore Hospital in a serious condition.
Firefighters had extinguished the blaze by around 9.45am, but remained at the scene .
The cause wasn't known yet.
Jonathan Asafo, who lives two minutes from the fire scene, was on his way to drop off his son in daycare when he spied the blaze.
"And as I drove past, I saw the whole house on fire and then I quickly reversed back and seeing as no-one was on the road and no-one knew the house was on fire, I quickly ... drove up the driveway and I started tooting my horn and then calling, running around for any response."
He saw a truck in the driveway, and with flames coming out of the house he ran to the neighbour's house and alerted them.
By the time he returned a survivor had made it out on to the back lawn. He had been sleeping downstairs, Asafo said, but he feared for his two friends who had been sleeping upstairs.
The young man was in shock, Asafo said, and the skin had burnt off his hands.
He escaped the fire after hearing Asafo's horn.
"He quickly went through the back door ...[he was] fully in shock."
By the time Asafo was talking to him firefighters had arrived.
Asafo did not know anyone living at the house.
"It's just sad that we weren't able to do anything more to rescue the other two but I guess being able to help one victim is better than [nothing]."
He was also worried for his three-year-old who was in the car in the driveway so moved his car away from the property.
A spokesperson said five crews and one command unit were sent to the fire.
Neighbour Lee Veo said she was waiting to find out the identity of the victims.
