Killers Nathaniel, Gareth and Stacey Train rigged up their rural home at Wieambilla in preparation for the lethal attack on four officers responding to an interstate missing persons report, the police union said.
Forensic examinations are continuing at the house in the western Darling Downs, where constables Matthew Arnold and Rachel McCrow and neighbour Alan Dare were gunned down on Monday.
Queensland Police Union president Ian Leavers said investigators believe the Train family planned the attack and were armed and ready to face a police assault.
"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 this murderous trio went to," he said.
Constable Keely Brough, 28, escaped the ambush by hiding in long grass, which the shooters set alight in an attempt to force her out, and is now recovering with her family.
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 might 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 has learnt a great deal about the fallen officers.
"The families are amazing people who had children who wanted to do great things in life," she said 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.
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.
