Mersane Warria was arrested after the bodies of eight children were found in the Cairns home.
Four girls aged 14, 12, 11 and two, and four boys aged nine, eight, six and five were found in Murray Street, Manoora, where the woman was also located.
Officers have not disclosed the cause of death of the children, but said knives were found at the house where the bodies were discovered on Friday.
Investigations were continuing throughout and police said autopsies on the children would also occur on Saturday.
Seven of the children found dead are siblings and the eighth child is a niece of the woman arrested, police said.
Charges would be laid when it was appropriate and everything's completed, Acting Assistant Commissioner Paul Taylor said.
"Overnight we had the forensic people in the house. The deceased have been removed from the house," Detective Inspector Asnicar said.
Australian Prime Minister Tony Abbott had said it was an "unspeakable crime", and that all parents would feel "gut-wrenching sadness at what has happened".
Flowers and teddy bears were laid near the crime scene and church services were held overnight in Cairns.
The incident comes days after an Iranian-born ISIS sympathiser took 17 people hostages and killed two of them before being gunned down by the forces in the 17-hour-long hostage drama at a cafeteria in Sydney on Monday.
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