UPDATE: 7.00PM An 18-year-old woman remains near a suspicious package inside a house on Sydney’s lower north shore, police say.
As the incident entered its sixth hour, a bomb disposal expert in full headgear was seen outside the home on wealthy Burrawong Avenue in Mosman.
Police said the woman was holding up well and was being reassured by trained officers.
Bomb technicians and negotiators are with the teenager in the house as a major operation involving the bomb squad, rescue squad and police continues, Assistant Commissioner Mark Murdoch told reporters.
The bomb is believed to be attached to the teenager in what is thought to be a ransom situation, although police have refused to confirm this.
The investigation is being led by the State Crime Command’s robbery and serious crime squad, which deals with extortion among other crimes.
Police found the teenager alone in the house on Burrawong Avenue after emergency services were called at 2.30pm AEST (12.30pm WST).
Although Mr Murdoch would not confirm reports the bomb is attached to the young woman, he said she remained in the house near the device.
“There’s a device in the house in the vicinity of the young woman. That device is still being examined as we speak,” Mr Murdoch said.
“We are treating the device as live until we know otherwise.
"We are working very hard to find out what it is and equally importantly what it isn't,” he said.
There are reports the device was attached to the woman by someone she didn’t know.
Mr Murdoch described the incident as “very sensitive”.
“We need to play our cards pretty close to our chest at this point,” he said.
“The young lady is fine and doing her best to assist the police to find out exactly what’s gone on,” he said.
Police said in a statement the incident was not being treated as self-harm.
Nearby homes on the street, where multi-million dollar properties include one belonging to horse trainer Gai Waterhouse, have been evacuated and nearby streets have been closed off.
The rescue squad is also at the house, and fire crews and paramedics are on standby.
A middle-aged man and a woman were seen with police officers outside the house, with the woman wiping tears from her eyes.
Investigators want to hear from anyone who noticed suspicious activity around the home or on Burrawong Avenue on Wednesday afternoon to contact Crime Stoppers on 1800 333 000.