Three people, including two police officers, have been shot and killed in an ambush at a remote property on Queensland's Darling Downs.
Another two officers were wounded when at least two gunmen opened fire at the rural property at Wains Road in Wieambilla at 4.45pm on Monday.
Police Commissioner Katarina Carroll said the alleged offenders were yet to be taken into custody.
The four officers responded to the isolated rural reporter to investigate reports of a missing person from NSW and were met with a hail of gunfire.
Police returned fire, but the two officers were critically injured and died at the scene.
An officer injured in the initial burst of gunfire was able to escape, while a second injured officer was located a short time later and taken to hospital.
The gunmen are understood to have taken weapons and police radios from the deceased officers, allowing them to track police movements as the investigation continues.
The commissioner fought back tears as she confirmed the deaths at the late-night media conference on Monday.
"Tragically ... two officers were shot and declared deceased at the scene. A member of the public was also shot and is deceased," Ms Carroll said.
"Those officers paid the ultimate sacrifice to keep our community safe."
"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.
"Tragically, this is the largest loss of life. We have suffered in one single incident in recent times.. It is devastating news."
Ms Carroll said the deaths would be "deeply felt" across Queensland before vowing the perpetrators would be brought to justice.
"It is sadly a reminder of the unpredictable nature of policing and the incredible dangers our officers face while protecting our community," she said.
"We are an organisation in mourning tonight, and at the appropriate time, we will honour the sacrifice these officers have made for us."
Prime Minister Anthony Albanese also said it was a heartbreaking loss for the families and friends of the Queensland Police officers who 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.
"Police officers face danger every day to keep us from it."
Premier Annastacia Palaszczuk said the deaths were a "horrible tragedy" as Western Downs regional council mayor Paul McVeigh said his community was shattered.
"It's an absolute tragedy in our community," Cr McVeigh said.
An emergency declaration remained in place on Monday evening for the Wieambilla area and Wains Rd is closed to the public.
Residents within Chinchilla Tara Road, Wieambilla Road, Bennetts School Road and Mary Street have been told to stay indoors until further notice.
The Queensland Ambulance Service is on scene, while two LifeFlight helicopters and the Rescue 500 chopper have been sent to the area.
Specialist police have also been deployed.
