Suzanne Williams, former head of the London Metropolitan Police unit for hostage negotiation, told the BBC: "The primary objective is to ensure the safety of the hostages above everything. Part of this is to reassure the hostage takers themselves - keep them calm, no surprises."

There has been strong criticism of people taking selfies earlier near the scene of the hostage taking incident, BuzzFeed reports, external. One tweet read: "People's lives are in danger and people are taking selfies in front of the Sydney siege, how disrespectful and idiotic."

BBC Trending

looks at where the hashtag #illridewithyou started. Thousands of people have now joined the spontaneous campaign, offering to meet Muslim people at their local stations and to ride with them on their journey.

Image source, Twitter/Boschma

It is late evening in Sydney now, and armed police have the Lindt cafe cordoned off and surrounded. This was the scene near the cafe a few moments ago.

Image source, Reuters

The Guardian has a piece on how the hashtag #illridewithyou, external is being used to spread a message of tolerance on social media. The newspaper says the trend was started by Tessa Kum, a TV content editor and writer living in Sydney.

The Huffington Post has brought together video and images , externalshowing the moments hostages fled the cafe.

No indications yet as to the hostage takers motives, but Anne Aly, head of the counter terrorism research programme at Australia's Curtin University, told the BBC's Outside Source programme he is likely to be working alone. "Certainly this appears to be the actions of a lone actor, perhaps not very well prepared, perhaps not very well planned, and the indications of the demands that he's making seem very odd for a hostage taking incident where you would expect materialistic or strategic demands to be made in connection with a particular group or cause."

The Sydney Morning Herald's editorial, external on the siege has "tested Australians as individuals, and Australia as a civil and democratic society". It says the next test will be for people in Sydney not to jump to conclusions about the motivations of the gunman.

Here's an update on the #illridewithyou hashtag on Twitter - it is currently the most popular trend worldwide, with more than 54, 477 tweets in the past hour.

The New South Wales government website , externalhas a map of the exclusion zone and will have updates on whether buildings such as the Supreme Court, which is nearby, will open on Tuesday.

tweets: , externalSydney is a safe & welcoming city, proud of its diversity. Great to see our best nature on show at a time like this. #illridewithyou

The Sydney siege is dominating Australian social media. The top ten terms trending on Twitter are on the situation, among them:

#sydneysiege - more than 30,000 tweets in the past hour, 252,000 in the past 24 hours

#illridewithyou - more than 24,000 tweets in the past hour. The hashtag emerged in the past couple of hours and in support of Muslims who may fear a backlash.

As the hostage story continues in Australia, armed men have reportedly taken a man hostage in Belgium. But the authorities there have ruled out a connection. "There is no indication that this is linked to terrorism, the Islamic State or what is happening at the moment in Sydney," the Ghent prosecutor told AFP.

tweets, external: We know who the hostage taker is. We will not be reporting it on the request of @nswpolice. Hope other media outlets follow.

Phil Mercer
BBC News, Sydney

says the PM Tony Abbott summed up the mood of the nation earlier when he talked about how terrifying it must be for the hostages to go into night-time having been held captive for more than 12 hours. One can only guess the fear, the panic, the terror going through their minds, our correspondent adds.

tweets:, external At 9:40am the cafe hostage siege started. It's now 9:40pm. http://www.buzzfeed.com/bradesposito/martinplace

BBC Monitoring

The Australia hostage story has gained very little traction among online jihad supporters, who are often quick to link incidents with their cause, BBC Monitoring reports. Only a few Islamic State supporters reported the news, with one saying that the motives of the hostage-taker were unknown. No claims of responsibility by any group have been seen by BBC Monitoring.

Wendy Frew
Australia editor, BBC News Online

says: "The police appear to be preparing for the possibility the siege will continue into Tuesday morning and possibly longer. Commissioner Scipione has made it clear he does not want to put any of the hostages at risk by rushing the operation and he indicated at his latest press conference he would be calling in more police."

A multi-faith vigil has been taking place at Australia's Lakemba Mosque, one of the country's largest. Samier Dandan, the president of the Lebanese Muslim Association, was there, and spoke to the BBC World Service's World Update programme, external: "The vigil crossed many different religious groups - Muslims, Catholics, Protestants, Jewish communities... This is a showcase and demonstration that the community can come together in solidarity and work together as a family to try to address whatever issue that we face collectively."

tweets, external: Unless you work in an exclusion zone, please go about tomorrow as you normally would. Exclusion zones can be found at http://www.nsw.gov.au/exclusion-zone-sydney …