Eight children have been killed and a woman who was mother to seven of them was injured in the northern Australian city of Cairns, police said on Friday, in what several media outlets reported was a mass stabbing.
Australia is in a state of heightened alert after police stormed a Sydney cafe early on Tuesday to end a 16-hour hostage standoff in which three people were killed, including the hostage-taker.
Queensland state police said in a statement they were called to a house in the Cairns suburb of Manoora just before midday after reports of a woman with serious injuries on the premises.
They found the bodies of the children, aged between 18 months and 15 years, when they were examining the location.
Detective Inspector Bruno Asnicar said police believed the woman was the mother of seven of the children.
"There is no formal suspect," Asnicar told reporters.
"We are talking to a range of people. Anybody who has had any involvement in the past two or three days is a person of interest," he said.
The woman, aged 34, was receiving treatment for her injuries, police said, and was assisting them with their investigation.
Forensics officers have locked down the scene and there has been no formal identification of the children.
While unrelated to the mass stabbing in tropical Cairns, the Sydney siege has triggered an outpouring of grief, with shocked Australians laying thousands of bouquets of flowers at a makeshift shrine in a central city mall near the siege cafe.
Prime Minister Tony Abbott called the events in Cairns "heartbreaking" and acknowledged that these were "trying days" for Australia.
"All parents would feel a gut-wrenching sadness at what has happened. This is an unspeakable crime. Tonight, there will be tears and prayers across our country for these children," he said in a media release.
Police in Cairns urged calm.
"There is no need for the public to be concerned about this, other than it is a tragic, tragic event," Asnicar said.
"The situation is well controlled at the moment and there shouldn't be any concerns for anyone else," he said.
Specialist officers were being sent from Brisbane, the state capital, to assist with the investigation, Asnicar said.
Media outlets reported that the neighbourhood was predominantly inhabited by indigenous Aboriginal Australians, and was known by residents to have a high crime rate.