A 21-year-old woman has died following a house fire on Queensland's Sunshine Coast, leaving her baby son without his mother. Isabella Nicholls, of Kallangur, sustained severe burns when her Buderim unit caught fire on Sunday night.

She was transported to the Royal Brisbane and Women's Hospital but succumbed to her injuries hours later, surrounded by her family. Two miniature dachshunds are also understood to have died in the blaze, which firefighters worked for an hour to extinguish.

A second woman, aged 32, was present at the unit but escaped the fire unharmed. Ms. Nicholls is survived by her infant son, Elijah.

"Our family is absolutely shattered by this unimaginable loss, and the heartbreak is beyond words," a family statement read. "Isabella was a vibrant, kind, and beautiful soul with her whole life ahead of her. She had a smile that could light up any room and a contagious laugh that none of us will ever forget."

The family added that she "touched the lives of so many people with her warmth, compassion, and beautiful spirit, and her absence has left an irreplaceable void in all of our hearts."

A fundraiser has been established to support Ms. Nicholls' memorial service, with the family stating, "We want to give her the beautiful and dignified farewell she deserves, while allowing our family the time and space to grieve without the overwhelming financial burden."

Investigations into the cause of the fire are ongoing, and police are considering all lines of inquiry. Detective Senior Sergeant Robert Lowry described the scene as "quite confronting for all of the emergency services that attended." He expressed sympathy for the family, noting that they are receiving support.

The entire complex was evacuated due to the proximity of the fire to a petrol station, and a public safety order was issued. Residents who were evacuated were permitted to return to their homes on Monday.

Authorities are appealing for anyone with relevant information, CCTV footage, or dashcam recordings to contact Crime Stoppers.