(CNN) -- For 10 long hours, the teen sat still as a bomb squad gingerly worked to remove a suspicious device strapped around her neck.
It was Wednesday afternoon in the affluent Australian suburb of Mosman when a masked man entered the home of 18-year-old Madeleine Pulver. He forcibly fit a strange object around her neck and fled.
Attached to it -- a note with "serious" demands, officials said without elaborating.
Bomb squads, negotiators and detectives rushed to the leafy suburb on Sydney Harbor, where sports stars and celebrities live.
Homes were evacuated; streets closed.
From a distance, Pulver's distraught parents -- well-respected and well-connected members of Sydney high society -- watched while four officers sat with her, keeping her calm.
But when the ordeal ended early Thursday, police discovered that the contraption they thought was a bomb contained no explosives. It was a hoax -- "a very, very elaborate hoax," said Luke Moore, the Australian police superintendent.
"We are treating this as an attempted extortion, a very serious attempted extortion," Moore said.
Now, police are looking for the person behind the act.
"We are unsure how the person we are looking for, the offender, gained entry to the premises, but certainly he managed to take Madeleine by surprise," police said.
Extensive "forensic examinations" are under way at the home, Moore said at a news conference Thursday.
"We have some initial lines of inquiry that we're following up and we will continue to do so."
Officers contacted explosives experts in Europe and the United Kingdom during the operation, said Mark Murdoch, the New South Wales police assistant commissioner.
"I'm not aware of anything like this happening in the country before, and I think that is what's made it so unusual," Murdoch told ABC Australia.
"Certainly the family is 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."
Pulver, who was taken to a hospital for assessment, was later released to her parents.
"I think she is waking up this morning in pretty good spirits," said her father, William Pulver.
"She is a little tired, a little sore from holding this damned device in place for about 10 hours," he said. "But she is now, as we are, eager to get on with her life."
Then, fighting back tears, he pleaded with the media for privacy.