Firefighters discovered the body of a person inside a burning shed in Portland in Victoria's south-west on Thursday night.
It comes as three people, including a 12-year-old boy, escaped with minor injuries in another house fire in Killarney, about 80 kilometres west of Portland.
CFA spokeswoman Andrew Brown said firefighters received Triple-0 calls at 7.30pm of reports of a shed fire in Hurd Street, Portland.
On arrival, about 20 firefighters found a shed behind a house engulfed in flames.
Ms Brown said it took 20 minutes for firefighters to gain control of the blaze so they could enter the building and inside, they found the body.
There were no reports of anyone else being home at the time.
Police are now investigating. A crime scene guard will monitor the property overnight and Portland Crime Investigation Unit detectives and an arson chemist will attend the scene of the fire in the morning.
In the second fire, which occured about three hours after the first, two women and a child suffered smoke inhalation from a burning washing machine in a house in Killarney.
Ms Brown said firefighters were called to the Mugavins Road at 9.50pm where they found the residents had dragged the burning washing machine outside of the house in an attempt to put it out themselves.
Investigations are continuing into the cause of the fire.