It involved the killing of police constables Matthew Arnold and Rachel McCrow, and neighbour Alan Dare, at a rural property in Wieambilla, a locality in Queensland.

New South Wales police reported that Gareth's brother Nathaniel Train, the former principal of Walgett Community College Primary School and Yorkeys Knob State School,[4] had not made contact since 9 October, and police were sent to conduct a welfare check as well as to follow up a warrant related to a December 2021 weapons dumping and a state border breach.

[5][6] Nathaniel's estranged second wife, who had lodged the missing person report on 4 December, had subsequently been inundated with threatening and vicious messages from Gareth.

[7] Gareth Train was an active participant in Australian conspiracy theory forums and websites: he had espoused strong anti-government, anti-police and anti-vaccine views, and supported the sovereign citizen movement.

[9] Gareth was a known online conspiracy theorist who claimed the Port Arthur massacre was a false flag operation which intended to disarm the Australian population[10] and that Princess Diana was killed in a "blood sacrifice".

[15] On 12 December 2022, police constables Matthew Arnold and Rachel McCrow from nearby Tara, and constables Randall Kirk and Keely Brough from Chinchilla drove in separate police vehicles to the property located at Wieambilla, a rural locality 270 kilometres (170 mi) northwest of the state capital, Brisbane.

[16][19][20][1] Nathaniel Train fired a single gunshot at Constable Arnold when he was 120 metres (390 ft) from the front gate, fatally wounding him in the chest.

[18][16] At 4:42 p.m., two constables from Dalby heard an urgent police radio broadcast that shots have been fired with an officer down and started heading towards Wieambilla.

[16][22] A wounded McCrow recorded a final message for her family on her body worn camera before emptying her police-issue Glock pistol at Gareth Train.

[16][23] Gareth began searching for Kirk who, after speaking to his supervisor on a mobile phone call, decided to flee to his police vehicle located 100 metres (330 ft) away.

[28] Prior to this, Dare's wife Kerry had called Triple Zero twice at 5:13 and 5:17 p.m., during which the operator advised against investigating the fire but failed to inform her before her husband and Lewis left that two police officers had been shot.

[16] At 10:29 p.m., SERT officers breached the property in the BearCat with assistance from two police helicopters who provided observations on the locations and movement of the perpetrators.

[45] Prime Minister Anthony Albanese paid tribute to the victims, labelling it a "devastating day" for the local community and for Queensland Police.

"[59][60][57] In December 2023, U.S. citizen Donald Day Jr, reported as being a conspiracy theorist, was arrested in the U.S. state of Arizona in connection with the shootings.

[62] In January 2024, prosecutors added further charges, accusing Day of illegal possession of a firearm and threatening FBI agents at the time of his arrest.