Emergency services were called at around 7am on Saturday 15 December 2018 to reports of a house fire in Woodhill Road, Collingham.
Area Chief Inspector Rich Stapleford said: “Tragically a boy, five, who was rescued from the house and taken to hospital has died.
“This follows the news that a girl aged eight and a woman aged 33 died following the incident.
“A 34-year-old man remains in hospital in a serious condition.
“Our thoughts are with the victims, their families, friends and the community of Collingham at this difficult time.”
It is believed that all casualties were members of the same family.
A joint Fire and Police investigation is taking place to establish a cause.
If you have any information call Nottinghamshire Police on 101 quoting incident number 189 of 15 December 2018.