Sydney, Dec 20 (IANS): Police Saturday arrested the mother of seven of eight children who were found stabbed to death at a house in Australia's Cairns city, accusing her of murder.

Mersane Warria, 37, was found after the horrific incident Friday with chest and neck wounds, Cairns Detective Inspector Bruno Asnicar said.

Seven of the children found dead are siblings and the eighth child is a niece of the woman arrested, police said.

Four girls aged 14, 12, 11 and two, and four boys aged nine, eight, six and five were found in Murray Street, Manoora, where Warria was also later found, ABC News reported.

Acting Assistant Commissioner, Paul Taylor said charges would be laid when it was "appropriate and everything's completed".

He said there were five fathers to the children, and police had been in contact with all.

Investigations are underway and police said that autopsies on the children would also occur later in the day.

Australian Prime Minister Tony Abbott described the killing of the eight children as an "unspeakable crime" and expressed grief over the incident.

This is the second shocking news to hit Australia in a week. Earlier this week, a gunman took hostage 17 people in a cafe in Sydney. Three people, including the gunman, were killed in the siege.