Police said it was too early to determine if arson was involved in the Grevillea Road blaze, which broke out just after 4pm in an empty weatherboard house.

The owner of the house said she arrived to find the property alight after her friend heard it on the scanner.

She said it was vacant but her mother's furniture was still inside.

Ballarat Police constable Brendan Davies said the cause was yet to be determined.

He said firefighters arrived within a couple of minutes of the triple zero call and brought the blaze under control.

Smoke blanketed the neighborhood, bringing dozens of curious residents out onto the street to observe the commotion.

Some onlookers said they thought the fire might have been deliberately lit.

Wendouree CFA captain Garry Drabsch said the station was high alert due to the heatwave conditions and firefighters were on the scene quickly.

But when they arrived the fire had already spread through the roof space, he said.

Mr Drabsch described the damage as "total loss".

Neighbor Sergio Carlos said he was washing his car when he noticed smoke coming from the next door.

"It started as a small fire and just engulfed quickly," he said,

His partner Shanae Seubert said they knocked on the door to make sure nobody was home, before calling triple-0.

One man who lived nearby said at one point the smoke was so thick he couldn't see the cars parked in the street in front of him.