Australian mother charged in deaths of eight children
Mourners visit a memorial near the house where eight children ranging from babies to teenagers were found dead in the northern Australian city of Cairns, December 20, 2014 (AFP)

The mother of all but one of eight children killed in the northern city of Cairns was charged with their murder on Sunday, Australian police said.

The 37-year-old, who has not been named and remains under guard in a hospital bed, was charged with eight counts of murder after the children's bodies were found Friday morning.

She appeared before a magistrate at the Cairns Base Hospital, Queensland police said in a statement.

Officers have not revealed the cause of death of the children -- four girls and four boys aged between two to 14 -- but said they were looking into various scenarios, including suffocation.

"We are considering that (suffocation) and that's why it's taking a bit of time," detective inspector Bruno Asnicar told reporters earlier Sunday.

Police previously said that knives were found at the house where the bodies were discovered.

Autopsies on the children were continuing and would be completed late Sunday at the earliest, Asnicar added.

The woman, who was arrested Saturday, has non life-threatening injuries, Asnicar added.

She is the mother of the seven younger children and the aunt of the 14-year-old girl.

Queensland Police have not named the family for cultural reasons. In some indigenous cultures it is considered disrespectful to say a deceased person's name.

The murders have rocked Australia, which is still reeling from a dramatic siege in a central Sydney cafe this week that left two hostages and a gunman dead and prompted a huge outpouring of emotion.