A Queensland police officer hurt in a shooting ambush and siege in which two fellow officers and a neighbour were killed has thanked "everyone from the Prime Minister down" for their messages of support.
Constables Matthew Arnold, 26, and Rachel McCrow, 29, along with 58-year-old resident Alan Dare were gunned down in an ambush and siege at the property at Wieambulla in the Western Downs region on Monday.
Constable Randall Kirk and Keeley Brough, both 28, escaped but the former was stuck by "intense fire from a variety of weapons", the police union said.
Constable Kirk, who is expecting his second child with wife Bree next month, is recovering from surgery to remove shrapnel and will soon be released from hospital to recover at home.
The couple says they are overwhelmed by the messages of support from the public and "everyone from the Prime Minister down".
"I'm feeling fine, just a little sore. My main thoughts are with the other police families at this awful time," Constable Kirk said in a statement released by the union.
"It means a lot to know the community cares for us all.
"My wife and I have a young family and would appreciate privacy as we come to terms with this "
Queensland Premier Annastacia Palaszczuk on Wednesday laid flowers at the Botanic Gardens Police Memorial in Brisbane as a gesture for those killed in Monday's attack.
"The constables were so young and brave, and Alan Dare, An innocent bystander," Ms Palaszczuk tweeted.
"We want the Queensland Police family to know that we respect and appreciate what they do for us. If you see an officer, please offer them a kind word as they grieve the loss of their colleagues."
Police are still probing the motive of Monday's attack, including whether the officers were lured to the property and the killers' links to extremist conspiracy groups online.
Their killers - former school principal Nathaniel Train, his brother Gareth and sister-in-law Stacey - died in a firefight with heavily armed tactical officers later that night.
Queensland Police Commissioner Katarina Carroll said investigators would look at the killers' possible extremist links after a series of posts under the name of Gareth Train were uncovered on conspiracy theory forums.
The posts include references to anti-vaccine sentiments and claims high-profile shootings were hoaxes or false-flag operations.
"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 night.
"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."
She 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.
