Her son had smashed a back window, concerned his other brother was still inside.
Thankfully, he was out walking the family's two dogs when the fire broke out.
The boy and his mother stood at the end of the driveway in disbelief as fire crews fought the blaze.
The woman said the house did have smoke alarms.
Senior station officer Bruno Saathof said they were called to the fire at 5.50pm.
Three fire trucks attended and it took them about half an hour to contain the flames.
He believed the teenager had been asleep and an electric heater had caused the fire.
An ambulance took the girl to Hawke's Bay Hospital in a critical condition.
There is extensive damage throughout the house with some of the ceiling fallen through, three quarters of the walls blackened from smoke and the flooring sodden and black from the fire hoses and ash.