A Middlemore Hospital spokeswoman said the two people injured in the fire were in intensive care in a stable condition.
The property belongs to first-home owners Chris and Jess Lawrence.
They told the Herald they had bought the home in December and were renovating it. During the final stages of renovation, they and their 1-year-old baby had moved in with Mr Lawrence's parents.
Yesterday's explosion occurred while the floors were being sanded.
"I'm really thankful that it didn't happen while we were there with our baby," said Ms Lawrence. She didn't know what had caused the explosion.
"A couple of guys were hurt, which is absolutely horrifying," she said.
Mr Lawrence said fire engines arrived within about five minutes of the first call.
Two WorkSafe investigators were at the scene yesterday.
"WorkSafe is making preliminary inquiries into the incident to determine whether or not an investigation will take place," a spokesman said.
It is understood maintenance on the house was being done by company Nick's Floorsanding.
A woman who identified herself as business owner Nick Afeaki's mother-in-law said she was very upset about what had happened and did not want to comment further.
