A mother has died hours after her three children and estranged husband were killed in a horrific car fire in the Brisbane’s east.

Police say Hannah Baxter, 31, succumbed to her injuries at the Royal Brisbane and Women’s Hospital.

It’s believed 42-year-old Rowan Baxter doused the car containing his wife and three young children in petrol before setting it alight.

Witnesses reported hearing the woman screaming “he’s poured petrol on me” as she managed to escape with critical burns.

The children — aged 3, 4 and 6 — died in the car.

There are reports Mr Baxter died nearby from a self-inflicted stab wound.

If you or anyone you know needs help, call Lifeline on 13 11 14.

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