A man is in custody after a woman's body was found in a burnt-out house in Melbourne's south-east this morning.

Detectives arrested the 38-year-old man at a residential address in Berwick just before 4pm.

The man lived with the 36-year-old victim at the Maria Court location with three children. The children were with the man when he was arrested.

Police are investigating how the woman died. Image: 9News (9news)

The womans body was found after emergency services extinguished a fire. Image: 9News (9news)

“Police will await the results of a post mortem regarding the exact cause of death, but it is being treated as suspicious,” Victoria Police said in a statement.

Emergency services were called to the blaze at around 10.45am and contained it within the hour.

Investigators are concentrating their hunt for evidence on the garage area of the singe-storey property.

The occupants of the house have since been located safe. Image: 9News (9news)

The body of the woman was found by police just after 10.30am after reporters of a fire.

“I don’t think there would be one person who isn’t affected by this,” City of Casey Deputy Mayor Amanda Stapleton told 9NEWS.

“Everyone knows each other in the community, we are very close. This is very devastating indeed.”

A post-mortem will be conducted by the coroner to determine the woman's exact cause of death.

Investigators are concentrating on the garage. Image: 9News (9news)

Police have spent the day gathering evidence from the site. Image: 9News (9news)

In an unrelated incident nearby, a man has been arrested after another woman’s body was found inside a home at Hampton Park.

Police were called to the Redwood Avenue address just before midday today, where a man was arrested at the scene.