A man in police custody since a "catastrophic" crash killed a 30-year-old woman and a 10-year-old girl has been confirmed as the partner of the woman driving and father and stepfather of the children in the vehicle.

The woman was in a vehicle with her two daughters and two sons, one of them a toddler, when it rolled early on Friday morning in the Indigenous community of Doomadgee, about 400 kilometres north of Mount Isa.

The mother died at the scene and her 10-year-old daughter was taken to Doomadgee Hospital, where she later died.

The three other children in the vehicle, each under five, were also injured.

A young girl remains in a critical condition. Her brother's condition has improved from critical to stable while in hospital.

A toddler received minor injuries in the crash.

Actin

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