28/04/2016 3:43 PM AEST | Updated 03/08/2016 12:34 AM AEST

Hundreds Gather At Port Arthur Memorial Service 20 Years On

Robert Cianflone via Getty Images
PORT ARTHUR, AUSTRALIA - APRIL 28: Australian Prime Minister Malcolm Turnbull speaks during the 20th anniversary commemoration service of the Port Arthur massacre on April 28, 2016 in Port Arthur, Australia. The historic town became infamous on April 28, 1996 when Martin Bryant began shooting indiscriminately with a high-powered rifle on people visiting the site. 35 people were killed and a further 23 were injured in what remains the world's worst massacre by a lone gunman. The tragedy transformed gun legislation in Australia, with then Prime Minister John Howard introducing the National Firearms Agreement, banning all semi-automatic rifles and all semi-automatic and pump-action shotguns and introducing stricter licensing and ownership controls. (Photo by Robert Cianflone/Getty Images)

Hundreds of people have gathered in Tasmania to mark twenty years since the Port Arthur massacre.

On April 28, 1996, gunman Martin Bryant killed 35 people and injured 23 others during a rampage. The massacre sparked nationwide gun reform in Australia.

On Thursday, Prime Minister Malcolm Turnbull addressed the crowd of hundreds, which included Former Prime Minister John Howard, Opposition Leader Bill Shorten, Foreign Minister Julie Bishop and Tasmanian Premier Will Hodgman.

"Despite the years, despite the healing, the sense of loss weighs heavy and we will never be the same. For those of you who lost loved ones and who witnessed the horror of what happened here, we will never truly understand the burden you bear and the pain that you endure. But on this day especially, you are not alone," Turnbull said.

"The tragedy united us with a rare intensity and it will be forever a legacy of those here on that day -- those who died and those who survived -- that gun violence in Australia is an exception rather than a brutal regular reality as it is, so sadly, in so many other parts of the world.

"They are the reason that Australia was moved to take the drastic action, the strong action, that it did. That action made form in the national firearms agreement is now held up around the world as an exemplar of a society refusing to relinquish control of its peace-loving existence."

Wreaths were laid in front of the cross bearing the names of the dead. The cross stands next to what was once was the Broad Arrow Cafe, where 20 people were killed.

The memorial service was only announced a few months ago after the 10 year memorial service was publicised as the last, with some Australians not wanting to revisit the pain of the past again.

But after many requests, the service on Thursday was held to pay tribute to the survivors of the day, particularly those who lost their lives, to remind a nation they are not forgotten.

Howard -- who early in his first term championed gun reform -- was the only politician to receive an official invitation.

Prime Minister Malcolm Turnbull and wife Lucy Turnbull lay a wreath beneath the cross.

John Howard is accompanied by Foreign Minister Julie Bishop to lay a wreath.