The Archbishop of Sydney is urging people to pray for those being held hostage in an Australian city cafe.

The Most Rev Anthony Fisher OP said: "Please join me in prayer for those held hostage in Martin Place, Sydney, and for the police who are trying to resolve the situation."

Some people have fled, but an unknown number remain inside with a gunman wearing an Islamic headband. Lindt have said 10 members of staff and around 30 customers were inside the chocolate shop and cafe at the time. 

A flag similar to the Islamic State symbol is being held up by hostages. 

The Premier of New South Wales, Mike Baird, is also asking for prayers. He has spoken to local Islamic leaders who have expressed their confidence in the police's work to bring the situation to an end. 

In a tweet, the Archbishop said: "I join with NSW Premier @mikebairdMP & police commissioner Scipione in asking everyone to keep the hostages in our thoughts & prayers."

The hostage attack began as Australians were making their way to work around 9am local time. It is now the evening, and police have made contact with the gunman. Eyewitnesses say the lights of the cafe have been turned off. 

Police officers are confident that no one has been hurt so far. 

Speaking to Premier Christian Radio, the Bishop for New South Wales said he was "more surprised" than others to hear the news. 

"Many thought it would happen," the Rt Rev Robert Forsyth said, "But I would say at first sight I did find it hard to believe.

"It's a place I know very well, it's near one of our churches.

"It's the shock of the unfamiliar, the violence in the midst of something you know so well, I think that's the shock."