 From 28–29 April 1996 Martin Bryant killed 35 people and injured 23 more in a mass shooting which became known as the Port Arthur massacre, during which he used a Colt AR-15 and a .308 L1A1 SLR.It was one of the deadliest mass shootings in Australian history and resulted in the "National Firearms Agreement" which restricted the ownership of all self-loading rifles and shotguns.In addition, the Australian government initiated a mandatory gun buyback program with the owners paid according to a table of valuations.