Police will investigate whether paranoid brothers lured unsuspecting officers to their deaths in a premeditated attack as details emerge they had turned their property into a “fortress”.

Nathaniel Train, a former principal, his brother Gareth and sister-in-law Stacey died in a firefight with heavily armed tactical officers after murdering two officers in western Queensland on Monday.

Constables Matthew Arnold, 26, and Rachel McCrow, 29, along with 58-year-old neighbour Alan Dare were gunned down in Wieambilla, in the Darling Downs region.

Details are emerging that the brothers who staged the deadly ambush were living off-grid, with locals suggesting they had built tunnels on the property, and have been linked to fringe online conspiracy groups.

Queensland Police Commissioner Katarina Carroll confirmed that “a lot of ammunition and weaponry” had been found at the remote address.

An aerial of the property at Wieambilla, 300 kilometres west of Brisbane. Photo: Nine News screenshot

Ms Carroll said investigators would look at the killers’ possible extremist links after posts under the name of Gareth Train were uncovered on conspiracy theory forums.

They include references to anti-vaccine sentiments and claims high-profile shootings were hoaxes or false-flag operations.

In one example unearthed by The Guardian Australia, Gareth Train posted about his mistrust for authorities, including the Queensland Special Emergency Response Team, which ultimately arrived at the property.

“If you are a conservative, anti-vaxx [sic], freedom lover, protester, common law, conspiracy talker, alternative news, independent critical thinker, truther, Christian, patriot etc etc expect a visit from these hammers,” he said.

Other posts include references to anti-vaccine sentiments and claims that high-profile shootings such as the Port Arthur massacre were hoaxes or false-flag operations.

One post refers to “black op police” and urges people to prepare themselves.

“Has reading anything from the 1901 constitution or quoting common law to the black op police with the guns helped anyone in Victoria and their rights,” a post from a user named Gareth Train said.

Ms Carroll said every possible motivation for the killings was being looked at, including whether it was a premeditated attack on the officers.

“Some of the stuff that’s online from these people, we will investigate what they have been doing not only in recent weeks but in recent years, who they’ve been interacting with … their online presence, every aspect of this will be thorough,” she said.

The police commissioner described the deadly shooting as “senseless and callous”.

“It’s very difficult at the moment for us to reason with what has happened, there are no obvious reasons,” Ms Carroll told ABC’s 7.30 program on Tuesday.

“But within the next few days and the next few weeks, I have no doubt that we will come back … [with] some insight into what we believe took place.”

A vigil was held in Brisbane for the slain police officers. Photo: AAP

Living in a fortress

It came as locals in the nearby town of Tara revealed chilling details of the brothers’ paranoid behaviours, including turning their property into a bunker.

Locals told Daily Mail Australia the Trains had spent years fortifying the weatherboard home and building tunnels as they set up elaborate defences.

The house was taken off-the-grid with solar panels, satellite dishes and rainwater and septic tanks.

“He said it had tunnels, fortified and barred doors and windows, guns everywhere and the boys [the Train brothers] had been taking ice lately,” a resident told the outlet.

Gareth’s wife Stacey had also worked as a teacher, with one former colleague at Tara Shire State College telling Daily Mail Australia she was a “COVID anti-vaxxer who refused to be vaccinated and so lost her job during the pandemic”.

Both Nathaniel and Stacey Train previously worked in the Queensland education system before the 46-year-old Mr Train moved interstate.

He was most recently executive principal at Walgett Community College Primary School. The NSW Department of Education said he hadn’t been employed in the state’s education system since August 2021, and he officially left employment in March.

While at the school in northern NSW, Mr Train sent 16 emails over two weeks about problems there and the need for assistance, the state’s parliament heard in May.

Nathaniel Train then seemed to disappear, cutting off contact with loved ones before returning to Queensland.

Stacey Train held a senior teaching post at Tara Shire State College before she resigned in December 2021.

-with AAP