The 2014 Sydney hostage crisis Confronting_problem , also known as the Sydney siege Besieging and Lindt Cafe siege Besieging , occurred Coming_to_be on 15–16 December 2014 when a lone gunman , Man Haron Monis , held Hold hostage ten customers and eight employees of a Lindt chocolate café in the APA Building in Martin Place in Sydney , Australia .

Police treated Coming_to_believe the event Confronting_problem as a terrorist Terrorism attack Attack at the time , but Monis ' motives were subsequently debated Communication .

Hostage Tori Johnson was killed Killing by Monis and hostage Katrina Dawson was killed Killing by a police bullet ricochet in the subsequent raid Attack .

Monis was also killed Killing .

Initially , many media organisations mistook Coming_to_believe it for the flag used Using by the Islamic State of Iraq and Syria ( ISIS ) ; Monis later demanded Request that an ISIS flag be brought Bringing to him .

Monis also unsuccessfully demanded Request to speak Communication to the Prime Minister of Australia , Tony Abbott , live on radio .

Monis was described Check by Abbott as having indicated Statement a `` political motivation , '' but the eventual assessment Judgment_communication was that the gunman was `` a very unusual casea rare mix of extremism , mental health problems and plain criminality . ''