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 Uber briefly charged its users in downtown Sydney a minimum $100 to escape an armed hostage crisis, a result of automatic surge pricing meant to get more drivers online. 
 
 An executive in the city's Central Business District (CBD) sent Mashable screenshots of the Uber app that showed the company was charging up to four-times the normal rate because "demand is off the charts." 
 
 Price surging was implemented in Sydney, Australia on Dec. 15th, 2014, during a hostage siege in the CBD. Image: Mashable 
 
 "I have never, ever seen it at four-times [the normal rate] and I'm a 1% top Uber user," said Matthew Leung, the user in contact with Mashable. "I understand the way the business works — higher the demand, higher the charge — but four-times at $100 minimum is ridiculous. Almost price gouging at its worst." 
 
 Another customer shared a screenshot of their "wack" fare estimate that showed a trip from an area just blocks from the siege to the airport would cost $145-185. That journey would normally cost less than $100, according to Uber's website. "This is price surging," he wrote in a comment to Mashable. 
 
 After Mashable published a story on the price hikes, the company reversed course and announced that all riders in the area would be free, and that anybody who had been charged the higher amount would be refunded. 
 
 "We are all concerned with the events happening in Sydney," Uber spokesperson Katie Curran told Mashable in a statement. "Uber Sydney will be providing free rides out of the CBD to help Sydneysiders get home safely." 
 
 Image: Uber 
 
 Any riders who were charged the higher amount may email supportsydney@uber.com to get their refund, she said, adding that surge pricing only remains in place to encourage more drivers to come online and pick up passengers from the area. 
 
 Uber, the company said, will now pick up the tab. 
 
 Uber Sydney's Twitter account tweeted the info. 
 
 Uber rides out of the CBD today are free for all riders to help Sydneysiders get home safely. See http://t.co/UIwoom25Bm for more info. — Uber Sydney (@Uber_Sydney) December 15, 2014 
 
 The crisis involves at least one hostage taker and about 13 hostages, all being held in a cafe in downtown Sydney, Australia. 
 
 At present, little is known about the assailant, other than the fact that an Islamic flag was shown in the cafe window, leading some to suspect that the incident may be a terrorist attack. Police have evacuated most of the area. 
 
 Following the police evacuation, many locals have reported difficulty in finding transportation as they attempt to exit the area. 
 
 Uber CEO Travis Kalanick had previously said the company's pricing algorithms will be "capped" during situations like what's unfolding in downtown Sydney. "For each market, the state of emergency price will be set after excluding the 3 highest-priced, non-emergency days of the preceding 2 months," he said, adding that the policy "intends to strike the careful balance between the goal of transportation availability with community expectations of affordability during disasters." 
 
 Last July, New York's attorney general announced that Uber agreed to put a cap on prices during “abnormal disruptions of the market,” meaning natural disasters and emergencies, to comply with the state's price gouging regulations. It isn't clear if a similar agreement is in effect in Australia. 
 
 Uber launched in Australia in Oct. 2012. 
 
 Seth Fiegerman contributed to this report. ||||| Media playback is unsupported on your device Media caption Jon Donnison: Footage showed people fleeing the building 
 
 A gunman is holding staff and customers hostage at a cafe in Sydney, Australia. 
 
 The Lindt cafe in the city centre is surrounded by armed police. Officers have made contact with the gunman. 
 
 Five people have been seen running from the building. It is not clear how many remain inside. A black Islamic flag has been displayed at the window. 
 
 Prime Minister Tony Abbott said it was "profoundly shocking" that people were being "held hostage by an armed person claiming political motivation". 
 
 He was speaking after chairing a meeting of the national security committee in Canberra. 
 
 Earlier Mr Abbott said: "Australia is a peaceful, open and generous society - nothing should ever change that and that's why I would urge all Australians today to go about their business as usual." 
 
 Senior police officers say they are on a footing "consistent with a terrorist event". 
 
 Media playback is unsupported on your device Media caption The mother of one hostage said her son sent a text saying "I'm ok" 
 
 The incident began as people were arriving for work in Martin Place on Monday. Witnesses saw a man with a bag and gun walk into the Lindt chocolate shop and cafe. 
 
 Lindt said about 10 employees and 30 customers were thought to be inside at the time. Nearby offices were evacuated and police asked people to remain indoors and away from open windows. 
 
 The BBC's Jon Donnison in Sydney says an enormous police operation is in place, on a scale few Sydney residents will have seen. 
 
 Image copyright Getty Images Image caption It is not clear whether the five who ran away from the cafe fled or were released 
 
 About six hours into the siege, three people were seen running from the building housing the cafe. Two more people followed about an hour later. It is not clear whether they escaped or were released. 
 
 New South Wales Police deputy commissioner Catherine Burn said: "Those people are now being assessed to make sure their health is okay and then police will talk to them." 
 
 "Our approach is to resolve this peacefully. It might take a bit of time but that is our priority," she added. 
 
 Media playback is unsupported on your device Media caption Eyewitness Andrea Proctor: "Many police officers started to come around us" 
 
 Police have identified the gunman and he is well known to them, Australian media report. 
 
 News organisations also say the suspect has contacted them to issue demands, which police have urged media not to report. 
 
 Channel 7, a broadcaster with offices facing the cafe, said lights inside the premises were turned out as night fell. 
 
 At the scene: Wendy Frew, BBC News, Sydney 
 
 The atmosphere in Martin Place itself was surreal. Office workers who had been evacuated from their buildings, construction workers from building sites and tourists packed the pedestrian plaza one block away from the Lindt coffee shop. 
 
 Rosemary D'Urso Healion had just come out of the Martin Place subway station and was walking to her office when she saw that it was blocked by police. Then she saw the police close down the subway station. 
 
 "I work in that building [where the siege is taking place] and I was just about to go in," she told the BBC, adding that she had been in contact with some of her colleagues who were in the building but not being held hostage. 
 
 She remained at Martin Place anxiously watching a police operation that appeared to be aimed at getting some of her colleagues out via a ladder erected on a window ledge on the first floor. 
 
 Uneasy crowds in Sydney 
 
 Eyewitnesses speak to the BBC 
 
 Image copyright AFP Image caption A man wearing a bandana and a backpack was seen inside the cafe 
 
 Image copyright AFP Image caption Hundreds of heavily armed police are surrounding the building 
 
 An armed man wearing a backpack and a bandana could be seeing walking around inside the cafe. 
 
 TV footage showed at least three people, thought to be employees and who were visibly distressed, holding up to the window a black flag bearing the declaration of Islamic faith, which reads: "There is no God but Allah, and Muhammad is his messenger." 
 
 The flag is similar to those used by jihadist groups, but is different from the one used by Islamic State militants in the Middle East. 
 
 Martin Place is home to the state premier's office and the headquarters of major banks. 
 
 In September Australia - which has sent fighter jets to join the US-led coalition conducting air strikes against Islamic State in Iraq - carried out a big anti-terror raid. 
 
 One man was charged with plotting to behead a member of the public in Martin Place. 
 
 In October, new anti-terrorism laws, including a provision designed to stop Australians fighting in overseas conflicts, were approved by the Australian parliament. 
 
 The black flag 
 
 Image copyright Reuters 
 
 A black flag bearing the white Arabic text of the "shahada", the basic statement of the Islamic faith, is used by jihadist groups worldwide 
 
 The statement says: "There is no God but Allah, and Muhammad is his messenger" 
 
 A black flag was the battle flag of the Prophet Muhammad and was carried into battle by many of his companions 
 
 Today, it is used as a symbol of engagement in jihad, in the sense of holy war, by militant groups including al-Qaeda and Islamic State 
 
 Islamic State's banner - unlike the flag raised in the window of the coffee shop - bears the first part of the shahada and the seal of the Prophet below it. 
 
 Timeline: Australia's terror threat
– An unknown number of hostages are being held at a chocolate shop and cafe in Sydney in what Prime Minister Tony Abbott says may be a politically motivated incident. Authorities say they're still working to find out how many people are being held in the Lindt Chocolat Cafe, where five hostages were seen running from the building after being captive for seven hours, the Sydney Morning Herald reports. Three men who ran from a fire exit were followed by two women, apparently cafe employees, who ran into the arms of police. Earlier, hostages could be seen holding up what appears to be an Islamic flag. Police say they believe there are no more than 30 hostages in the cafe and as far as they know, nobody has been harmed. It's not clear whether there's more than one gunman involved. Hundreds of police officers have locked down part of the city's central business district and police presence has been massively boosted in other Australian cities. The police commissioner for New South Wales says the situation is tightly contained and officers are trying to resolve the situation peacefully, the Guardian reports. He did not confirm or deny reports that radio host Ray Hadley had spoken to a hostage acting under instructions from a gunman. Abbott said at a press conference that Australians should go about their lives as normal but stay alert, the BBC reports. "I can think of almost nothing more distressing, more terrifying than to be caught up in such a situation, and our hearts go out to these people," he said. Uber, meanwhile, now says it's offering free rides out of central Sydney. At the start of the hostage crisis, the company quadrupled its prices to a minimum $100 Australian, saying "demand is off the charts," Mashable reports.