Sergeant Glen Huitson was by all accounts already a hero when he was shot and killed by Rodney Ansell, the real-life inspiration for Crocodile Dundee.

In his 12-year policing career, Sergeant Huitson had already had boiling water poured on him in one incident, received a commendation for disarming a drunk person threatening another with a knife and star picket in 1995, and then, six months before his death, received a valour award after he disarmed a rifle-wielding man threatening bus passengers in Litchfield National Park.

On Saturday, several hundred people gathered to remember the officer at a service marking 20 years since his death, just metres from where he was shot in Darwin's rural area.

He was the last officer to be killed on duty in the Northern Territory, and the only one in the past 70 years.

NT Police Officer Glen Huitson, who died while on duty in 1999. ( Supplied )

"We must not forget what happened that day out here; we lost one of our own," said Paul McCue, head of the NT Police Association.

"All our police go to work each and every day not knowing what's in front of them, not knowing which stranger they will need to protect that day, or what incident they will need to resolve," he said.

"No one, most of all his family, was to know Glen would not come home on 3 August 1999, but he didn't, and he was gone.

"The bloke who brought people together — no matter what your background, race, religion, or beliefs — was taken far too soon as he went to work that day, protecting the NT community."

'Crocodile Dundee' on the loose

The gunman who took Sergeant Huitson's life was Rodney Ansell, a former Territorian Of The Year, and the man who inspired Paul Hogan's character in the global hit film Crocodile Dundee.

In 1999, his life was on a downward drug-induced spiral, a far cry from the man who charmed the TV talk show circuit in the wake of the movie's success.

But Ansell was resentful he didn't receive the recognition he felt he deserved, and so for reasons unknown, he went on a shooting spree.

Rodney Ansell, who shot and killed police officer Glen Huitson, in 1999. ( Supplied )

He fired indiscriminately at a house while its occupants took cover inside; a young girl inside hid in a wardrobe as the bullets kept whizzing by.

"Bullets were going through the walls and out other walls and through the floor and so we're just laying there not moving," said Dave Hobden, who lived in a neighbouring house.

He went over to investigate, but as he jumped into his truck, Ansell fired a shot through the windscreen, nearly costing him an eye.

"I couldn't see anything by this stage, my face was all blood — I didn't know what had happened," he said.

Mr Hobden's neighbour lost part of his hand as he attempted to confront the gunman.

A reporter remembers

The next morning, the shooter was still at large.

As the ABC's police reporter, I was sent to cover the shooting, but it was the day after the Darwin Cup, and I must admit to feeling a bit dusty.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 2 minutes 7 seconds 2 m 7 s 1999 ABC Darwin news report on the shooting of Sergeant Glen Huitson

A police roadblock had been set up on the Stuart Highway near Old Bynoe Road, which was being manned by Sergeant Huitson and Constable Jamie O'Brien, who'd been there for a few hours.

Journalists had gone to the roadblock and were told to wait at a nearby police command post, and police were about to reopen the highway when the bullets starting flying.

The sound of gunfire was enough to snap me out of my post-Darwin Cup haze as an officer threw a bulletproof vest over my head.

Next minute it was being ripped back off again — maybe they realised there weren't enough to go around.

The next thing I remember was an ambulance flashing by.

What we didn't know then, was that in the back was a police officer fighting for life.

Constable James O'Brien shot and killed gunman Rodney Ansell. ( ABC News: Alan Dowler )

Sergeant Huitson had been hit in the side of his chest when Ansell sneaked up on the roadblock through the bush and opened fire.

Another ambulance flashed by, this time containing a young man, Jonathan Anthonysz, whose only crime was being in the wrong place at the wrong time.

He and his mate Anthony Hobden had been chatting to police at the roadblock.

"Jonno's calling out 'he's been shot, get me out of here, get me out of the line of fire', … [I] went and dragged him back behind the police car," Mr Hobden said.

But a bullet shattered his lower back.

He survived the ordeal but was told he'd probably never walk properly again.

After much surgery, he did eventually manage to walk, but to this day his legs still give out on him occasionally.

Ansell was killed in return fire by Constable Jamie O'Brien, who shot him in the chest.

Hero 'just doing his job'

The memories of that day are as raw now as they were then, said Acting Police Commissioner Michael Murphy.

"There is not a day that goes by that Glen is not remembered by everyone that knew him, worked alongside him, or was impacted by his life and death," he said.

A tribute to Sergeant Glen Huitson, killed in the Northern Territory on 3 August, 1999, on the 20th anniversary of his death. ( ABC News: Alan Dowler )

Sergeant Huitson's father John said he was very impressed by how many people had gathered to remember his son.

"You just can't imagine how many people have come to this place, he must have been pretty popular," he said.

"He had a very strong mind, when he wanted to do something he'd do it. Never got into trouble as a kid or nothing, never had any problems with him whatsoever."

But when asked if he thought his son was a hero, he said: "I don't think he'd think he was, just doing the job."

Sergeant Huitson's son Joe was only two and his daughter Ruby was just nine months old when he died.

"Every day I think about 'what would he do, what should I do?' I know he dedicated his life to helping others and I'm trying to do the same," Ruby said.

Sergeant Huitson's wife Lisa said he wouldn't have liked the fuss of the memorial, and was happier out of the limelight, doing his job out of love for the community.

"I wanted the children to know the world was still a good place … and their father's there watching over them," she said.

"I didn't want them to miss out on anything because what they had taken away from them was so, so horrible."

Sergeant Glen Huitson's daughter Ruby, wife Lisa, and son Joseph at the 20th anniversary memorial of his death. ( ABC News: Alan Dowler )

Former NT Police Association president Vince Kelly said he vividly recalled the day of Sergeant Huitson's funeral two decades ago.

"I could never forget the devastation etched on Lisa's face as she grappled with the grief, trying to make sense of the loss of her husband, best friend, and father of her children," he said.