Thousands of people are expected to gather on one of the toughest days for Queensland Police as constables Matthew Arnold and Rachel McCrow are farewelled in Brisbane.

A memorial service with full police honours will be held for the two early-career officers, aged 26 and 29 respectively, on Wednesday after they were gunned down at a rural property at Wieambilla on December 12.

Queensland Police Union head Ian Leavers said it was going to be a very difficult day for both the families of the murdered officers and the force.

“Matthew and Rachel will be side by side. They worked together, they died together, and they will be farewelled together,” he told Nine’s Today show on Wednesday.

“Police are travelling from all over southeast Queensland, as we speak, to attend, as well as from many other areas within the state.

“It will be a very emotional service, and many hearts are going to be broken.”

Queensland Police Minister Mark Ryan said the force was grateful for the show of support from the public following the tragedy.

“I don’t think there is a single police station that hasn’t had a truckload of flowers delivered to it,” he said on Tuesday.

“It’s been a tough week but they’ve very much appreciated the show of support.”

Some 8000 free tickets were made available to the public to attend the service, which will commence at 10am local time at the Brisbane Entertainment Centre and be attended by Police Commissioner Katarina Carroll, Premier Annastacia Palaszczuk and Opposition Leader David Crisafulli.

It is anticipated thousands of officers will stand on Melaleuca Drive to salute as the funeral procession passes. The guard of honour will include a police band, mounted unit and dog squad along with police vehicles and motorcycles and helicopters. 

The ceremony will be broadcast live with a number of public screenings around Queensland, including in the communities of Tara, Dalby, Chinchilla and Miles near the site of the tragedy at Wieambilla, three hours west of Brisbane.

Speeches will be made by dignitaries but the main focus will be on the eulogies by the officers’ family members and friends.

Ms Palaszczuk is encouraging Queenslanders to buy a ribbon from local police stations for a small donation as a show of support.

Ms Carroll said the two officers didn’t stand a chance when they came under fire alongside two other officers at the rural property.

“The fact that two got out alive is a miracle,” she said following the shooting.

Two other young constables were Keeley Brough and Randall Kirk.

The officers had gone to the property as part of a missing persons check and were met by a hail of gunfire fired by Gareth Train, his wife Stacey and his brother Nathaniel.

Neighbour Alan Dare was also killed when he went to check on a fire lit to flush out Const Brough as she took cover in the bush.

The shooters later died in a firefight with specialist officers several hours after the four constables first arrived at the scene.

Investigators are yet to officially declare a motive but are examining known links between the Trains and extreme conspiracy theorist groups and forums.