Beenleigh mum dies days after unit fire which killed her toddler son

A Queensland woman has died in hospital days after being injured in a unit fire which killed her three-year-old son.

Crystal Cartledge, 30, was rescued from her two-storey flat in Beenleigh on Sunday night by neighbours, who punched through glass to save her.

The mother-of-five had suffered burns to 90 percent of her body and had been on life support in the Royal Brisbane and Women's Hospital.

Her three-old-son, Baileigh, died at the scene.

Ms Cartledge's partner Tom Berie, who is in his 30s, and two of her four other children, one-year-old Vanessa and five-year-old Adam, suffered minor injuries.

Police have refused to rule out that the fire was deliberately lit.

"It's still under investigation, and no cause has been determined," a police spokesperson said.

Police will start to interview witnesses in the coming days.

Donations from neighbours and strangers have poured in via the Logan House Fire Support Network, with $11,000 raised so far.