Three ambulances and one clinical manager were also sent to the fire.
"We assessed and treated one patient with serious injuries who was transported to Middlemore Hospital," a spokesperson from St John said.
Counties Manukau CIB's Detective Senior Sergeant Veronica McPherson said police were continuing to investigate the circumstances of a death in Manurewa on Saturday night.
"A scene guard remains in place at the Nina Place address, with a post-mortem to take place in due course.
"As part of this formal identification procedures are still to be carried out."
The male occupant of the address remains in Middlemore Hospital, McPherson said.
Earlier police had said they would continue to investigate the circumstances surrounding the fire, supported by Fire and Emergency New Zealand.