Discarded cigarette butts are believed to have started a fire at a house in Bell St in Whanganui.
Emergency services were called just before 11am on Thursday. Clouds of smoke were billowing from the roof and sides of the building and police cordoned off the Bell St block between Glasgow St and London St.
Fire and Emergency Senior Station Officer Aaron Summerhays said the fire was contained to one part of the house.
"There was heavy fire development in that part of the house and smoke damage to the rest of the building.
"A fire safety officer has investigated and it appears the fire was accidental due to discarded cigarette butts.
"We've had a high number of structure fires lately so we want to remind people to ensure ovens and heaters are turned off after use and that fire ashes and smoking material is disposed of properly."
Bell St resident Michelle Davey works a night shift as a caregiver and was getting ready to go to bed when the fire erupted.
"It just sounded like a gunshot, one bang, I was about to ring the police and then everyone came.
"I saw four people come out of the house with a dog and saw smoke rising from the end room."
Other neighbours said they only realised something was happening in the street when they heard fire and police sirens.