Six dead in shootout in rural Australia

Four officers arrived at a tree-lined property near the small town of Wieambilla late Monday afternoon.

"As soon as they entered the property, they were inundated with gunfire," said Queensland Police Union president Ian Leavers, "they never had a chance."

"Two police officers were executed in cold blood," he said.

The deceased were identified as 26-year-old Rachel McCrow and 29-year-old Matthew Arnold. Both joined the force in the last two years and were still constables.

"Those officers paid the ultimate sacrifice to keep our community safe," said Queensland Police Commander Katarina Carroll, holding back tears as she briefed the public on the "extraordinarily distressing" events.

A 58-year-old neighbour believed to have heard the commotion and investigated the scene was also shot and "declared deceased at the location", according to police.

- A 'heartbreaking' day -

Two other officers survived the attack and were taken to hospital with minor injuries.

One of the survivors was Constable Keeley Brough, who sent frantic messages to loved ones as suspects tried to smoke her out of surrounding bushland where she hid, local media reported.

She has been a police officer for just eight weeks, officials said.

Aerial images from the scene showed an unremarkable zinc-roofed bungalow, a burned-out vehicle and smoke still lingering around the property.

After an initial clatter of gunshots, a specialist team of more than a dozen officers with air support was rushed to the scene.

By 10:30 pm local time, following an hours-long siege, two male suspects and one female suspect were dead.

Police did not reveal the suspects' identities, but officers were believed to have been searching for a former primary school principal who went missing late last year.

Local media reported the property was registered to the missing man's brother and sister-in-law.

It is believed the brother was a regular poster to conspiracy theory websites, railing against "secret societies" and shadowy intelligence agencies conducting "(false) flag operations."

Investigations are under way into the incident and police handling of the situation.

Mass shootings are rare in Australia, which has some of the toughest gun laws in the world.

A ban on automatic and semi-automatic weapons has been in place since a 1996 mass shooting in Port Arthur, Tasmania in which a lone gunman killed 35 people.

Prime Minister Anthony Albanese described the scenes in Wieambilla as "terrible".

It was, he said, a "heartbreaking day for the families and friends of the Queensland Police officers who have lost their lives in the line of duty".

Queensland officials have ordered flags to be flown at half-staff at government buildings.