Parents of a Brisbane toddler who has died in hospital with severe burns did not seek medical help for days, police have alleged.

Police said the couple told them their child had been accidently burnt in a hot bath several days ago, but said investigations into how the burns occurred were ongoing.

Detective Inspector Tim Trezise said Maddilyn-Rose Stokes was in a critical condition and unconscious when paramedics arrived at the townhouse in Ridge Street at Northgate, in Brisbane's north, about 3:00pm on Thursday afternoon.

He said she had very severe burns to her feet, legs and buttocks.

"The injuries certainly are, on first glance, consistent with that story. At this stage we have no reason to disbelieve that," he said.

However, he said police had "a very open mind" given the burns likely caused the girl's death.

"One would assume that medical would have been sought [before Thursday]. To this point we haven't been able to establish that medical treatment was sought," he said.

Neighbours say they were shocked by the incident, saying nothing seemed out of the ordinary at the house. ( ABC News: Candice Prosser )

Inspector Trezise said the girl was at home with her father, 30, and mother, 23.

The parents are assisting police with inquiries and no charges have been laid.

"It's a very sad and tragic event, and nobody is more traumatised, can I say, than her parents," Inspector Trezise said.

The home has been declared a crime scene and a report will be prepared for the coroner.

Child Safety Minister Shannon Fentiman said the Department of Child Safety was not currently investigating or involved with the affected family.

"My heart breaks for the family and friends of this little girl. There are many people grieving today," she said.

'Nothing out of the ordinary'

Neighbour Rhonda Jones said she was at home all day and did not hear anything at the house until emergency services arrived.

"I thought, something terrible is happening down there, there were police and ambulance people everywhere so I thought this is really bad," she said.

A man and woman are helping police with their inquiries after the two-year-old's death. ( AAP: Glenn Hunt )

"There was nothing yesterday that would make anyone think something had happened because it was all so quiet, I was here all day and I never knew anything had happened until I heard all the sirens."

Ms Jones said she would smile and wave at the family but did not know them well and did not see anything out of the ordinary.

Ms Jones was shocked to find out the child had died.

"It's awful, she was only a child, so young, it's terrible," she said.

"I was just absolutely amazed, it's really, really terrible."