He has been identified as Tori Johnson, who had been store manager at the Lindt Chocolate Cafe for over two years.
According to reports, Tori noticed that the gunman Man Haron Monis was starting to doze off.
The male hostage noticed and used the opportunity to try to wrestle the gun from the hostage-taker.
At some point there was a shot, and it was this activity that caused the sniper hiding in Channel 7 to believe there was a gunshot and orders were given to rescue the hostages.