Three young girls, including an eight-month-old baby, were found dead after their mum told police she had killed her children, the force says.
The 31-year-old woman, said to be from Nepal, allegedly told officers she wanted to kill herself when she called an emergency number in Vienna, Austria.
The girls were suffocated, according to a preliminary investigation.
Officers were sent to the family's apartment in the suburban Donaustadt district at 5.20am on Saturday, and arrested the mum, who had self-inflicted injuries, a spokesperson said.
The bodies of three children - aged nine, three and eight months - were then found inside the home.
The eldest girl was taken to hospital where attempts to revive her were unsuccessful.
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Investigations remain ongoing while officers determine if the woman is fit to be questioned.
The background to the incident is currently unknown, police said.
The initial investigation revealed that the children were suffocated, the Wiener Zeitung newspaper reported.
Police were speaking to relatives of the mother, who is from Nepal, and were told that the girls' father is believed to be living in Vienna, but was separated from their mum, the report added.
In a statement, a police spokesperson said: "Today in the early hours of the morning a woman, aged 31, called the police emergency number and stated that she had just killed her children and now wanted to kill herself."
The mum was discovered first as the emergency services arrived at the flat. She had non-life-threatening injuries and was immediately detained, according to reports.
The police spokesperson added: "During an immediate search of the home, the police found two girls, aged eight months and three years, who were dead.
"A third girl, aged nine, was taken to hospital, but resuscitation was unsuccessful."
"At the moment, the initial criminal investigation is taking place at the crime scene.
"A forensic medical report on the cause of death is still pending.
"A statement from the suspect is not yet available.
"The background to the incident is still unknown."
Post-mortems were due to take place later on Saturday.
