A Queensland mother is set to be charged with murder after a ferocious house fire in Toowoomba left three of her children dead, in what police believe was a deliberately lit blaze.

The fire tore through the family’s Harristown home just after midnight on Wednesday, engulfing the property in flames and thick smoke.

Emergency crews rushed to the scene, but the home was already consumed by flames.

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A boy was found dead near the front door.

His two young sisters were pulled from the blaze in critical condition and rushed to Queensland Children’s Hospital.

Tragically, both girls died shortly after being taken off life support.

Queensland Police suspect the 36-year-old mother started the fire intentionally.

Neighbours say they heard arguing at the home in the hours before the fire.

7NEWS understands she will be charged with murder.

The woman remains under police guard in hospital with critical injuries and is expected to face a bedside court hearing once her condition stabilises. This could take several days.

Two other children survived the blaze, along with the woman’s 34-year-old partner.