Three people have been shot and hostages may have been taken at a factory on the outskirts of Sydney, Australian police said on Monday, although it was not immediately clear what had sparked the incident.
A spokeswoman for the New South Wales state police said authorities believed three people had been shot.
Australian media reported that one person was killed and two were wounded and taken to hospital, although police could not immediately verify those reports.
"Negotiators and a tactical response team are at the scene and trying to gain access to the building," the police spokeswoman said.
In December 2014, a lone gunman and self-styled sheikh who claimed allegiance to the Islamic State militant group took 17 hostages at a cafe in central Sydney.
The gunman and two hostages were killed in the final minutes of the 16-hour siege.