Seven Network reporter Chris Reason, who was watching the siege unfold from his newsroom across the road, said some of the hostages broke free after Monis attempted to usher the hostages from one side of the café to the other.
One man emerged from the cafe with his hands up and lay down on the ground in front of police. Seconds later, a group of at least five hostages escaped from the cafe.
It is believed that Monis then fired his shotgun, reportedly killing one of his captives. This appeared to be the trigger for tactical police to move in.
Within seconds, they had blasted through the cafe door and opened fire with automatic weapons, also hurling what appeared to be stun grenades. The sounds of explosions echoed through the city, and the flashes of rifle fire and the grenades lit up the area.
The gunfight lasted less than two minutes, and more hostages emerged after the police raid.
As the scene calmed down, a bomb disposal robot was seen entering the cafe.
Self-proclaimed Islamic cleric Man Haron Monis, a 49-year-old man living in southwest Sydney, came to Australia from Iran as a refugee in 1996.
He first came to the attention of authorities when he started sending hate mail to the families of Australian dead soldiers between 2007 and 2009, according to The Daily Telegraph.
The siege in the Lindt cafe in Martin Place on Monday reportedly followed an unsuccessful effort to have a conviction related to penning those letters overturned in the High Court on Friday, according to The Age.
Monis received 300 community service hours and a two-year good behaviour bond for the correspondence, which he claims were his version of sympathy cards and sent with the help from his girlfriend Amirah Droudis.