This video can not be played
Suspect detained after Darwin shooting
On Tuesday, four people were killed when a gunman went on a rampage across the northern Australian city of Darwin.
It's Australia's third mass shooting since a lone gunman murdered 35 people in Port Arthur, Tasmania in 1996, after which gun laws were heavily overhauled.
But experts say what makes the Darwin case different is that it's the first mass shooting since then that was not isolated to one property and which used an illegal weapon.
Mass shootings are defined by the Australian Institute of Criminology as those resulting in at least four deaths excluding the perpetrator.
They're rare in Australia because, say experts, it has some of the toughest gun laws in the world.
The previous two mass shootings since Port Arthur were the murder-suicide of a family of five in New South Wales in 2014, and seven deaths at a rural property in West Australia in 2018.
Both were acts of domestic violence by a male perpetrator, shooting and killing members of his own family on a single property.
"They were licensed shooters, using legally owned firearms, being used in horrific acts of domestic violence," says Associate Prof Philip Alpers from the University of Sydney, who has studied mass shootings in Australia.
But in Darwin, the "active shooter" warning began at a motel in the city, before the alleged gunman travelled to four other locations, including to the outskirts of the city.
Authorities say it was not terror-related but have not identified the victims or the suspect.
"These were shootings in several locations across a city rather than one family household," says Associate Prof Alpers.
"We don't yet know this wasn't domestic violence, but we do know this person was not using a legally allowed firearm."
He points to the fact the alleged gunman was on parole and fitted with an electronic ankle bracelet.
In addition, witnesses have said they heard many rounds of bullets in quick succession but the legal pump action shotgun only shoots five rounds of bullets, Associate Prof Alpers says. Police have confirmed this was a prohibited, stolen firearm.
The crackdown after Port Arthur included tough restrictions on gun ownership and the banning of semi-automatic and automatic firearms.
The government also bought back and destroyed more than a million firearms. In another amnesty in 2018, more than 57,000 weapons were handed over.
But Australians now own more guns in total than they did before this 1996 crackdown, according to figures from 2016 – the last time they were comprehensively studied.
But gun ownership per capita has dropped by 23% during the same time. This shows fewer people have guns in their homes, but some own many more guns.
Allow Twitter content?
"Unlike America, we're unused to an incident with eight crime scenes across a city like this," Dr Clarke Jones, criminologist at the Australian National University, told the BBC.
He said the rarity of the incident "doesn't mean our gun laws have failed by any means".
Associate Prof Philip Alpers agrees that such incidents are "very unusual in Australia".
"The Northern Territory does have more firearms per capita than any other jurisdiction because of agriculture, which is perfectly legitimate."
But he says the fact the gunman was "able to obtain such a firearm in his circumstances says we still have a way to go to get guns off the 'grey market' – unregistered guns that were kept by households after 1996."
Darwin is a small city with a population of just under 137,000 people.
Residents there have expressed their shock, with one, Darwin Recycling manager Peter Boden, telling NT News: "You see these things happening over in US, I never thought I'd see it happen here."
Prime Minister Scott Morrison has paid tribute to Darwin's "close knit" community while Northern Territory Chief Minister Michael Gunner said: "This is not the Darwin we know."
The suspect remains in police custody at the Royal Darwin Hospital and is due to be charged with murder.
Heroes pulled Venice crash survivors from burning wreck
Actor Julia Ormond sues Weinstein for assault
FTX crypto empire 'built on lies' – prosecutors
Indigenous rights vote is a reckoning for Australia
McCarthy has gone. What happens now?
Deserted Karabakh reveals scale of military defeat
India-China feud keeps planes out of Nepal airport
Watch: Inside Paris flat as bedbugs take over city. Video
Bedbug panic sweeps Paris as infestations soar
The guardians of Peru's Potato Park
Marriage equality eludes Japan's same-sex couples
How Mike Jeffries used shirtless models to sell Abercrombie
The companies paying for workers' holidays
The dress that shocked the world
A place with air so clean it's bottled
© 2023 BBC. The BBC is not responsible for the content of external sites. Read about our approach to external linking.