Neighbours were woken by the sound of an "explosion" during a house fire that killed an elderly man in Wainuiomata early this morning.
Firefighters were called to the blaze at a flat in Burden Avenue about 2am.
Once extinguished, crews searched the home and found the deceased man, who was believed to be the sole occupant.
The flat, one in a complex of six, was damaged extensively, police said.
Neighbour Munny Groenewegen, 79, said she and her 91 year-old-husband were woken by an explosion.
"We had to leave, because it was so big, all of a sudden."
Initially she thought the explosion had come from her own house, because it was so loud.
"When I looked outside of my window and saw the big flames, I knew that we had to get out."
She and her husband were evacuated by a neighbour, and were kept in a police car to keep warm while their son arrived.
Police are yet to name the deceased man, and neighbours say he lived alone.
Ms Groenewegen said he was "friendly" and quite active, often seen on walks or playing his organ.
"He was quite nice, we used to talk over the fence when he was sitting in the garden."
She suspected the explosion may have been caused by a small gas heater the man owned.
A scene examination is still being carried out by fire investigators to determine the cause of the fire.
Police communications manager Nick Bohm said police investigators have been unable to access the site due to unsafe conditions, and fire crews were still dousing the area.
Mr Bohm said it may take some time to identify the man, but police were working to contact next of kin who may be overseas.