A gunman who killed four people and injured another in the Australian city of Darwin used an illegal pump-action shotgun, police say.
The 45-year-old suspect, who was known to police, was arrested about an hour after the first shots were fired on Tuesday.
Police said the gunman carried out attacks at several locations and may have been searching for a “specific individual”.
It was not terror-related, they added.
Authorities have not identified the victims or the suspect.
Mass shootings in Australia have been a rare occurrence since the country overhauled its gun laws in 1996, in the wake of a shooting in Tasmania that left 35 people dead.
Those reforms included restrictions on gun ownership and the banning of all semi-automatic and automatic firearms.
The weapon used on Tuesday was a prohibited 12-gauge pump-action shotgun, said Northern Territory Police Commissioner Reece Kershaw.
The alleged gunman, who had been on parole since January, was wearing an electronic tag at the time.
Police said he travelled to several places across the city, including the Palms Hotel in the suburb of Woolner. There he allegedly opened fire in a number of rooms before fleeing.
One person was reportedly killed at the motel while another person was wounded.
Another person was killed at Buff Club, another at Gardens Hill Crescent and another at Jolly Street. Police said the suspect also went to the Peter McAulay Centre – a police operations base.
Witnesses said the suspect appeared to have been searching for a specific person called “Alex”.
“We know he was looking for one individual,” Commissioner Kershaw told reporters on Wednesday.
The suspect remains in police custody at the Royal Darwin Hospital and is due to be charged with murder, he added.
Northern Territory Chief Minister Michael Gunner said officials would conduct an urgent review of all prisoners on parole in the wake of the shootings.
“The Northern Territory Government will do everything in its power to determine what led to these tragic events and how this violence occurred,” Mr Gunner said.
Australia saw its worst mass shooting incident in more than 20 years last year when seven members of the same family died in a murder-suicide.
More recently, a man was killed and three others wounded in a shooting outside a popular nightclub in Melbourne in April.