A six-year-old girl who was taken to Hospital after a suspected stabbing in Melbourne's north has died, Police have confirmed.

Emergency services were called Kellaway Crescent in Mill Park about 7.50pm in response to reports of a stabbing.

A woman, aged 39, was also pronounced dead at the scene.

Police said they found a man, woman and a girl, who are believed to be known to each other, with critical injuries.

The young girl was taken to hospital in a critical condition, where she died.

Police said the man, 40, who is under police guard in hospital, is also in a critical condition.

Anyone with information should call Crime Stoppers on 1800 333 000.