Australian bomb squad officers on Wednesday safely removed a teenager from a "suspicious device" media reports said had been strapped around her neck, ending a 10-hour drama.
Police were alerted by the 18-year-old schoolgirl, said to be a member of one of Sydney's wealthiest families, in the exclusive suburb of Mosman in the early afternoon and fire crews and paramedics were placed on standby.
The Sydney Morning Herald said a balaclava-clad man had earlier entered the house and placed the device on the girl, although police would not confirm the suggestion that it was strapped to her or if it was indeed a bomb.
Other reports said a ransom note was attached to her neck and it was a case of extortion, with the Sydney Daily Telegraph citing a senior police officer referring to the device as a "collar bomb".
Assistant Commissioner Mark Murdoch later told the Australian Associated Press (AAP) that the girl had been freed from the device, which was intact, and reunited with her parents.
"We still don't know if it was explosive," he said, declining to say if the incident had been an extortion attempt.
"Certainly the family are at a loss to explain this, but you wouldn't expect someone would go to this much trouble if there wasn't a motive behind it," Murdoch was quoted as saying.
"The family have endured something no one needs to endure ...but they have held up remarkably well," he added.
Investigations were being headed by the robbery and serious crimes squad, which also deals with extortion attempts.
Mosman is a wealthy suburb on Sydney's lower north shore lined with million dollar homes.
The street where the incident was playing out is also reportedly home to leading racehorse trainer Gai Waterhouse and ex-Australian rugby stars Phil Kearns and John Eales.