SYDNEY, Australia — The police said four people were shot and killed on Tuesday in Darwin, the capital of Australia’s Northern Territory, when a gunman went on a shooting spree in the city’s main business district.
The Northern Territory police said at least one additional person had been wounded, and that a 45-year-old man had been arrested within an hour of shots being fired. The man had been on parole, the police said.
The authorities said the shooting was not an act of terrorism. A video showed three officers in military camouflage subduing the man.
“We’re still trying to establish the intent and motivation behind this, but all I can say, sadly, is that people have lost their lives this evening,” Reece Kershaw, the Northern Territory police commissioner, said at a news conference in Darwin.
Witnesses told Australia’s public broadcaster that the rampage appeared to start just before 6 p.m. at the Palms Motel, where a gunman carrying a pump-action shotgun fired several rounds before moving to other nearby locations.
“He shot up all the rooms, and he went to every room looking for somebody, and he shot them all up,” John Rose, a witness, told the public broadcaster. “Then we saw him rush out, jump into his Toyota pickup and rush off.”.
The shooting in Darwin, a former frontier outpost with a population of about 130,000, seemed to be Australia’s deadliest since May of last year, when seven members of a Western Australia family were found dead in an apparent murder-suicide. That was the country’s worst mass shooting since the 1996 Port Arthur massacre in Tasmania, which left 35 people dead and led to a significant toughening of Australia’s gun laws.
Experts typically define a mass shooting as the deaths of four people, excluding the gunman, in a single event.
After the Port Arthur killings, Australia banned assault rifles and many other semiautomatic rifles and shotguns. It established a major gun buyback program, buying firearms — mostly banned weapons — from owners who turned them in. It also imposed new registration requirements and restrictions on gun purchases.
Polls show more than 90 percent support in Australia for the two-decade-old gun regime. But the country has also been gradually loosening its laws in recent years, and gun sales are increasing. Those who own guns, own more guns — in some cases, 100 or more. Sales of semiautomatic handguns, which are not as regulated as rifles, have skyrocketed.
In the Northern Territory, for example, the number of gun owners declined to 13,000 in 2014 from almost 15,000 in 2007, according to Gunpolicy.org, a clearinghouse for gun data. But the number of privately owned firearms increased to almost 64,000 from less than 47,000 in the same period.
Violent crime in the territory has been on the wane, with assaults and domestic violence declining over the past year, according to state crime statistics.
But Commissioner Kershaw said the man who was arrested Tuesday had been known to the police. Without identifying him or his previous crimes, he said the man appeared to have been released from prison in January.
He wouldn’t say whether the shooting appeared to have been premeditated.
Prime Minister Scott Morrison, speaking to reporters traveling with him in London, offered his condolences to the loved ones of the victims, who were also not identified.
“This is a very tight community, and I know they will be rocked by this event,” Mr. Morrison said.