Multiple fatalities, man arrested after shooting in Darwin

A man who allegedly opened fire in Darwin on Tuesday night, killing four men and injuring a woman, can be identified as 45-year-old Ben Hoffmann.

Hoffmann was on parole and wearing an electronic monitoring bracelet when he allegedly opened fire with a pump-action shotgun in the Darwin city area about 5.45pm local time (6.15pm AEST) on Tuesday.

Darwin shooting suspect Ben Hoffmann. Credit: Facebook/Ben Hoffmann

The shooting spree began at a motel just outside the city centre, before the alleged gunman travelled to several other locations, including to the outskirts of the city.

Police arrested Hoffmann, known to his friends as "Hoffy", in the Stuart Park area of Darwin at 6.45pm.

Television footage showed a man on the ground after being dragged from under a white dual cab ute, kicking his legs at officers from NT Police's Territory Response Group. Hoffmann remains in custody, and no charges have been laid.

NT Police Commissioner Reece Kershaw said officers were able to track down the suspected gunman after he contacted a police duty superintendent, who alerted others to his location.

"He asked to be placed into protective custody, which we did," Commissioner Kershaw said. "We do believe he may have been trying to hand himself in. We're not sure."

Hoffmann is being held in Royal Darwin Hospital.

A former friend of Hoffman said he was "a normal guy growing up", but had been in and out of jail in recent years.

The friend said he saw Hoffmann earlier this year and "he seemed normal. He was friendly. Happy to see me. I saw him again later but I avoided him, like you might do with people you know who are in and out of jail".

Commissioner Kershaw said the suspected gunman was "well-known" to police and previously had a number of adverse interactions with the police force.

Commissioner Kershaw described him as having links to outlaw motorcycle gangs

He said Hoffmann was released on parole about January this year after serving at least a year.

Police are still trying to establish the motivation behind the shooting.

Police arrest a man in Darwin on Tuesday after four people were shot dead and one was injured.Credit: ABC News

"Unfortunately and sadly, four people have lost their lives this evening," Commissioner Kershaw said.

A police operation is ongoing in Darwin, with more than 100 police officers examining crime scenes including the Buff Club, Palms Motel, Coles Express and the Peter McAulay Centre, police headquarters, as they trace the suspect's steps.

Commissioner Kershaw said the alleged gunman might have tried to enter the police facility at some stage.

A NT Health spokeswoman said two people were taken to Royal Darwin Hospital in a stable condition.

Witnesses saw man with gun

The incident started with reports of a man firing shots at Finnis Street about 5.50pm just outside the Darwin CBD, with the four deaths occurring at the nearby Buff Club, Gardens Hill Crescent, the Palms Motel and Jolly Street.

Witness John Rose told the ABC he saw a man walk into the motel with a "sawn-off shotgun".

"He shot up all the rooms and he went to every room looking for somebody and he shot them all up, then we saw him rush out, jump into his Toyota pick-up, and rush off," Mr Rose said.

Other witnesses said they heard what sounded like firecrackers. A woman told the ABC she saw a man with a shotgun, and gave first aid to a woman who had been shot in the legs.

Police cordon off a block of units where a person was shot.Credit: AAP

Max Campart was having a drink at the Punters Bar, across the road from the Palms Motel, when he heard about seven or eight shots.

Patrons were told to move towards the back of the bar and stay away from the windows.

"We didn’t know exactly what was happening. It was very loud," Mr Campart said.

While inside the pub, he glimpsed the alleged gunman walking down the street about 50 metres away.

"I saw a guy coming down the street in a white T-shirt with a gun in his hand," Mr Campart said.

The man thrashed around on the ground as police stood over him.Credit: ABC News

A group of about a dozen men who were friends and relatives of a man who died at the Palms Hotel gathered outside after the shooting and many were in tears.

Darwin resident Matthew James was standing in a car park nears the Palms when it all began.

"It was just surreal," he told Nine's Today program. "All of a sudden there were these gunshots.

"Moments later someone came running towards me carrying this woman who was covered in blood and just basically put her at my feet and she was screaming that she had been shot.

A police crime scene at an industrial complex on Jolly Street in Woolner on Wednesday.Credit: Michael Franchi

"The guy that actually carried her up was pretty frantic at the time, saying he had opened the door and there was a gunman there with a shotgun and he proceeded to fire upon anybody inside the building."

The woman was hysterical, Mr James said.

"She was caught up in it. She said, 'I've been shot, I don't know why, I don't have anything to do with anything,' he said.

The woman told Mr James the alleged gunman had been going from room to room, firing his gun and shouting the name "Alex".

"It just seems so insane," Mr James said.

'Terrible act of violence'

Prime Minister Scott Morrison said the shooting was a "terrible act of violence" and said he had been in contact with police and NT Chief Minister Michael Gunner.

"I just want to send my deep condolences and sympathies to all the people in the territory and particularly in Darwin," Mr Morrison said from London.

"This is a very tight community and I know they will be rocked by these events.

"I think it’s important that everyone in Darwin, everyone in the territory, understands that the thoughts of Australians [are with them]."

Mr Gunner said: "This is not the Darwin we know."

"On behalf of Territorians, our thoughts are with the families and friends of the victims and everybody else who has been impacted," Mr Gunner said.

"I thank our police and first responders."

Marietta Martinovic a criminology expert, from RMIT University, whose research specialises in electronic tag monitoring and reoffending said it was "extremely rare" for a suspect to commit a large-scale crime when wearing a monitoring bracelet.

"Most people that are put on bracelets are very aware of the fact and research shows that our highest risk offenders are least likely to reoffend while wearing a bracelet," she said.

Dr Martinovic said that, if the offender had been wearing a monitoring bracelet during the alleged attacks, authorities would have been able to track his moments in near real-time.

"It is extremely rare. Most people, before they decide to reoffend, they would certainly cut the bracelet off."

with Nick Miller in London, AAP, Ben Weir