Five hostages have fled a siege in a Sydney city centre cafe but more are still being held inside by an armed offender.
Australian officials have not confirmed how many people are still inside the Lindt Chocolat Cafe, which was seized by an armed man at the height of the morning rush-hour, and have warned it could stretch into a second day.
What appeared to be a black Islamic State flag was put in the window of the cafe soon after the attack began, fuelling speculation that it was the work of an Islamic extremist.
Five people later made their way out, though police would not say whether they escaped or were released.
Mike Baird, the premier of New South Wales, has called on his state to pray for those who are still being held,
"I'm certainly proud of how we have responded as a city, state and nation," he said.
"But my thoughts remain with those that are caught in this event, and my call goes out to the state to pray for them, and to pray for their families."
Mr Baird said he and Police Commissioner Andrew Scipione had spoken to Islamic leaders in recent hours: "We are in this together ... Ultimately, we are doing all we can in these difficult circumstances, and we will get through it."
An exclusion zone will remain in place overnight around Martin Place, at the heart of the city's legal, financial and political district, and office staff based within that zone have been asked to work from home tomorrow.
Mr Scipione said the priority for police was to bring the hostage crisis to a peaceful end.
Journalists working across the road at the Channel Seven newsroom, who have a direct line of sight into the cafe, said they believe there may be 15 people still inside.
Mr Scipione moved to reassure the remaining hostages: "Rest assured, we are doing all we can to set you free."
It is believed some of those inside have been posting on social media and have contacted a number of media outlets.
He also confirmed that one of the five hostages who have made it out of the cafe had been treated at a hospital, but said this was for a pre-existing condition.
"I understand that no-one's been injured, and for that, if that is true, we are grateful," Mr Scipione said.
He has also refused to confirm reports that the hostage-taker was known to police prior to this morning's events.
Nor would he comment on the offender's motives: "There would be many out there that are guessing. At this stage, we're not in the business of speculating - we're in the business of investigating."
He said police did have a line of communication to the gunman, who may be scanning social media.
"The means by which we're communicating are something we'd like to keep close to our chest," he said.
Mr Scipione said Sydney landmarks including the Opera House - which were emptied earlier in the day - "have been cleared and deemed safe".
Australian Prime Minister Tony Abbott said he could not think of a more "distressing or terrifying" event to be caught up in than the unfolding incident.
He said there were "some indications" that the siege could be politically motivated, while police said they could not yet rule out terrorism.
Mr Abbott said: "We don't yet know the motivation of the perpetrator. We don't know whether this is politically motivated, although obviously there are some indications that it could be.
You can follow live coverage of the events in Sydney with our rolling news blog here.
"We have to appreciate that, even in a society such as ours, there are people who would wish to do us harm.
"That's why we have police and security organisations of the utmost professionalism that are ready and able to respond to a whole range of situations and contingencies including the situation that we are now seeing in Sydney.
"The whole point of politically motivated violence is to scare people out of being themselves. Australia is a peaceful, open and generous society. Nothing should ever change that and that is why I would urge all Australians today to go about their business as usual."
A man who works at the cafe, and arrived for work just after the siege started, said he saw one of his colleagues pressed up against the window.
Nathan Grivas said the building was already locked when he arrived.
"I didn't get a good look at them - as soon as I saw the gun, all I wanted to do was get out," he said.
Prime Minister David Cameron said he had been briefed overnight on the siege, adding: "It's deeply concerning and my thoughts are with all those caught up in it."
One of Australia's largest mosques, at Lakemba in west Sydney, released a statement signed by a number of Islamic organisations including the Australian National Imams Council and the Australian Federation Islamic Council.
"The Australian Muslim community shares with fellow Sydneysiders their utter shock and horror at the unprecedented scenes emerging from the Lindt cafe in Martin Place this morning. Our immediate thoughts go to the hostages and their loved ones," the statement said.
"We pray for their safety and hope this matter is resolved quickly and peacefully. We reject any attempt to take the innocent life of any human being, or to instil fear and terror into their hearts.
"Any such despicable act only serves to play into the agendas of those who seek to destroy the goodwill of the people of Australia and to further damage and ridicule the religion of Islam, and Australian Muslims through this country...
"This is a time for all Australians to stand together and support each other. We pray for a swift resolution to this crisis with no injuries or loss of life."
Ten News anchor Hugh Rimington said on Twitter: "Ten news has received a video in which a lindtcafe hostage relays the gunman's demands. At police request we will not broadcast it."
Several local media outlets said they are complying with a police request not to relay the offender's demands.
