Police investigating 'absolutely tragic' death of baby found in Ballarat

The head of a family support service says the death of baby girl in the Victorian city of Ballarat is "absolutely tragic".

Homicide squad detectives are investigating after emergency services were called to a residential address in the suburb of Redan on Sunday and found the eight-month-old unresponsive.

Victoria Police said CPR was administered before she was taken to Ballarat hospital just after 1pm.

She was then moved to a Melbourne hospital, where she died on Tuesday.

The ABC understands the baby had been living with foster parents but had been returned to her biological parents.

Child and Family Services chief executive Wendy Sturgess said the death has caused widespread hurt in the community.

"It impacts everybody who has been involved with the baby," she said.

"[It's] absolute sadness and disappointment that we are here — it doesn’t even sum it up.

"It's our job to keep children safe, especially babies."

Police say a 23-year-old man has been interviewed and released.

The Homicide Squad is continuing to investigate the death. Anyone with information is urged to contact Crime Stoppers.