SYDNEY Australia's world-famous Sydney Opera House was evacuated after a suspicious package was found on Monday morning, soon after a hostage crisis broke out at a cafe in downtown Sydney.
Local media reports said the airspace over the city's central business district has been shut down .
Hostages are being held in Lindt Chocolat Cafe in the heart of the shopping and financial district in Sydney. Some of them were seen holding a black flag with white Arabic writing, raising fears that the incident is linked to Islamic militants, said local reports.
There were reportedly about 20 staff and customers in the shop and some of them could be seen waving at the window.
Witnesses reported hearing loud bangs that sounded like gun shots.
Australian police have cordoned off the area around Martin Place, home to the Reserve Bank of Australia, commercial banks and close to the New South Wales (NSW) state parliament.
Sydney Morning Herald said a man armed with a gun has held up the shop, but other local media reports said there were more than one attacker.
Patrick Byrne, a producer at Channel Seven whose newsroom is opposite the cafe, said staff at the television station watched the situation unfold.
"We raced to the window and saw the shocking and chilling sight of people putting their hands up against the panes of glass at the cafe," he told the Australian Broadcasting Corporation.
"This was just extraordinary."