Arson and Explosives Squad detectives have this morning arrested a woman in relation to the fatal house fire in Point Cook yesterday morning.
A 46-year-old woman was arrested in Airport West.
She remains in police custody.
Her arrest comes after a fatal house fire that claimed the lives of three people in Totem Way yesterday morning.
Emergency services were called to the property following reports of a house fire which had spread to nearby residences about 3.40am.
The townhouse was destroyed by the blaze and two neighbouring properties were also damaged.
Arson chemists forensically examined the property late into the evening on Wednesday.
It is believed the woman was known to the one of the occupants of the property.
Police are not looking for anyone else in relation to the matter.
A 19-year-old woman, a 28-year-old man and a three-week-old baby girl died in the fire.
The investigation remains ongoing and anyone with information is urged to contact Crime Stoppers on 1800 333 000 or make a confidential crime report at www.crimestoppersvic.com.au