[KeyLargo]

The muzzle flashes and sounds on the video you can see that the police used automatic weapons inside the building.

http://nypost.com/2014/12/15/gunman-in-sydney-seige-idd-as-islamist-hate-preacher/

[MeshugeMikey]

Im told they used flash grenades..perhaps in addition...to the weapons fire

[BunnySlippers]

I thought that was a flash bang device.