Two people feared dead in a house fire that killed a woman near Ballarat in central Victoria have been found safe.

A 43-year-old woman died when flames engulfed the weatherboard home on Greenhill Road in Mount Helen in the early hours.

Police said two people in their 20s who were unaccounted for, and thought to be the woman's children, had been found in Ballarat.

Senior Sergeant David Hermit said: "There were two or three people who were unaccounted for. They have been found and are safe and well."

He also said "an unidentified body... is about to be recovered."

Neighbours reported hearing an explosion about 1:30am and seeing flames which destroyed the property.

Arson chemists have arrived at the scene and will try to establish the cause of the blaze.

But regional duty officer Cade Dowey said the destruction caused by the fire had made it difficult for investigators to get inside.

"Unfortunately the roof has collapsed and fallen into the insides of the house, which again has hampered our crews in the ability to put the fire out," Officer Dowey said.

"It's also made the scene quite unsafe for anybody to enter the house, hence why the investigation and searching for the people has taken so long."