Three shooters rigged a sophisticated surveillance system to help them "take police out" at a remote Queensland property where they ambushed officers, killing two constables and a neighbour.
Forensic examinations are continuing at the Wieambilla house, in the Western Downs region, where constables Matthew Arnold and Rachel McCrow and neighbour Alan Dare were gunned down on Monday.
Queensland Police Union president Ian Leavers says there's evidence killers Gareth Train, his wife Stacey and brother Nathaniel, who were all shot dead in a siege with officers, planned the attack and set up a camera system.
"It was a sophisticated surveillance system and that is very, very concerning to us - knowing that this ruthless, murderous trio went to this extent with a view, I firmly believe, to take police out," he told ABC Radio on Thursday.
Mr Leavers said he didn't want to hamper the police investigation into the incident, but police were very concerned about the attack.
"It's sickening to know the lengths that this murderous trio went to," he said.
Constable Keely Brough, 28, who escaped the ambush by hiding in long grass, which the shooters then ignited, is taking time off with her family, he said.
Her colleague, Constable Randall Kirk, who also got away, is recovering at home with his daughter and pregnant wife after having surgery to remove shrapnel from his leg.
Mr Leavers said Const Kirk may need further operations, but both officers were doing as well as could be expected.
Queensland Police Commissioner Katarina Carroll met with the families of constables Arnold and McCrow and said she had learnt a lot about the two officers.
"The families are amazing people who had children who wanted to do great things in life," she said on Thursday.
Details about a memorial service for the fallen officers are expected in coming days, while community gatherings are planned for Tara and Chinchilla, near Wieambilla, on Friday.
Western Downs mayor Paul McVeigh said the community was deeply saddened by the tragedy but had come together in tribute.
"The outpouring of support and gestures of sympathy and condolences from the residents and businesses of Chinchilla and Tara have been heartwarming at a time when such pain and sadness is being felt," he said.
Political leaders paused to honour the police officers killed in the shooting tragedy in federal parliament, including a tearful tribute from Opposition Leader Peter Dutton.
Mr Dutton, a former Queensland police officer, said three wonderful Australians had paid the ultimate price while serving their community.
"Three people who embodied compassion, commitment and courage during their lives and in their final moments," he said.
Home Affairs Minister Clare O'Neil said while authorities searched for answers, the national security implication of online extremism would have to be examined.
"There will be important questions we will need to consider on how our country deals with acts of violent extremism, but today is not the day," she said.
"Today is a day for grieving."
Police trying to identify the motive for the lethal attack have been tracing the brothers' online activities, including posts in the name of Gareth Train that featured a mix of conspiracy theory-laden material.
The Train brothers' father Ronald Train said he struggled to comprehend how his sons, who cut ties with him 23 years ago, could be responsible for the killings.
"They went down this track, this dark track, which we have no understanding of," he told Nine's A Current Affair program on Wednesday.
The now-retired pastor officiated at the wedding of Nathaniel and Stacey some years ago, adding he was surprised by reports his older son Gareth was now married to the same woman.
© AAP 2022