A house fire that was extinguished by the Whanganui Fire Brigade on Magnolia Crescent on Tuesday is believed to have started after cooking was left unattended.
The fire started in the kitchen and spread through the roof of the home, causing extensive damage.
Whanganui Fire Brigade senior station officer Bryan Coskerie said a fire investigator was looking into the matter.
"When the fire brigade arrived, it was fully smoke-logged and there is smoke damage through the whole house," Coskerie said.
"We had a fire in the roof of the house. It started in the kitchen area and we believe that the fire probably started from unattended cooking."
One man was outside the home when firefighters arrived at the scene just after 4.50pm on Tuesday and he had suffered burns to his hands.
He was treated by St John ambulance officers at the scene who evaluated his injuries as moderate and transported him to Whanganui Hospital.
Coskerie said it was important to have working smoke alarms.
"The home did have working smoke alarms, although I'm not sure whether or not they alerted [the occupant] to the fire," he said.
"People need to be vigilant and ensure that they don't leave the kitchen unattended when they're cooking."
Firefighters had extinguished the blaze by 5.36pm, leaving thick clouds of dark smoke billowing through the air.
A neighbour who did not want to be named saw the fire after it began.
He saw another neighbour running towards the house and another who had a fire extinguisher in hand as emergency services including police arrived.
"It was really dark, black smoke. The smoke was so thick, you couldn't even see probably 100 to 150 metres ahead," the man said.
"We were worried because when they opened a window, we thought it might burst. We could feel the smoke. I had to move away, it was a bit hard to breathe."
The status of the occupant is not known.