Police shot dead three people following a siege on Queensland’s Darling Downs on Monday night, which ensued after the two officers and a neighbour were gunned down.

Constables Matthew Arnold, 26, and Rachel McCrow, 29 were responding to a call for a missing person when confronted by a “hail of gunshots” after jumping a fence, Queensland Police Union president Ian Leavers told ABC Radio National on Tuesday.

The pair were shot and fell to the ground, while two of their colleagues took cover behind them.

“The ruthless, murderous trio have then gone and executed the two police, our fallen officers, who were on the ground. They have executed them in cold blood,” Mr Leavers said.

The three people who confronted police at the property at Wains Road, Wieambilla, then allegedly lit a fire in an effort to coax out a young policewomen taking cover in long grass.

“She actually believed that she was either going to be shot or she was going to be burnt alive,” Mr Leavers said.

A siege situation ensued and specialist police and PolAir responded.

“Two males and a female were fatally shot during a confrontation with police shortly after 10.30pm,” the force said in a statement early Tuesday morning.

AAP has been told the three attackers were killed in a firefight with officers. According to police sources, the men were brothers and the woman, one’s partner.

Police Commissioner Katarina Carroll said the horrific incident was devastating for the victims’ families and the entire organisation.

The commissioner fought back tears as she confirmed the initial deaths of the three people, including her officers, at a media conference late Monday night.

“I would like to also pay tribute to all police and first responders who assisted at the scene and are continuing to respond this evening,” she said.

“Tragically, this is the largest loss of life we have suffered in one single incident in recent times … It is devastating news.”

An emergency declaration remains in place for the Wieambilla area and a crime scene has been established at the property.

Prime Minister Anthony Albanese earlier said it was a heartbreaking loss for the families and friends of those who had lost their lives in the line of duty.

“My condolences to all who are grieving tonight – Australia mourns with you,” he tweeted.

Opposition leader Peter Dutton, a former Queensland police officer, was also moved by the tragedy.

“Deeply distressing news coming out of western Queensland tonight with those police officers who have been murdered,” he wrote.

Premier Annastacia Palaszczuk said the deaths were a “horrible tragedy” as Western Downs regional council mayor Paul McVeigh said his community was shattered by what was “an absolute tragedy in our community”.