Gunmen take hostages in Sydney cafe

Live television footage on Monday showed patrons inside a cafe near the New South Wales state parliament with their hands pressed against the windows.

As many as 20 people are reported to be in the cafe, and there are at least two gunmen inside, witnesses said. Police said an operation was underway.

Witnesses also reported hearing loud bangs at the scene.

A black and white flag, similar to those used by "Islamic State" militants, could also be seen in the window.

"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," news producer Patrick Byrne told the Australian Broadcasting Corporation.

"This was just extraordinary," he said.

Police have cordoned off part of Martin Place, the site of the Reserve Bank of Australia and a number of other commercial banks, and advised people to avoid the area.

Prime Minister Tony Abbott has convened Australia's National Security Committee for emergency briefings on the situation.

"This is obviously a deeply concerning incident but all Australians should be reassured that our law enforcement and security agencies are well trained and equipped and are responding in a thorough and professional manner," Abbott said in a statement.

Meanwhile, the world-famous Sydney Opera House was evacuated after a suspicious package was discovered, local media reported.

cmk/bw (Reuters, AFP, dpa)