Officers found the man in his "late 40s" with critical head and leg injuries from an assault when they were called to a disturbance at the Anzac Avenue motel after midnight on Friday.
Paramedics administered first aid but the man who was local to the area died at the scene.
Two men - aged 37 and 41 - and a 28-year-old woman are assisting officers after they were discovered nearby by the dog squad a short time later.
"The information that we have is that the people are known to each other," Senior Sergeant Tracey Martin told reporters.
A crime scene has been established at the motel.
Snr Sgt Martin said a number of items had been removed from the scene as part of their ongoing investigation.
"I do understand a variety of things have been identified and we're trying to ascertain which of those were related and which of those were not," she said.
"We believe an assault has occurred. A post mortem has not been conducted at this stage ... so we're still trying to establish what the extent of those injuries were."
Queensland Ambulance Service had tried to treat the man at the scene before he died.
They said a second, uninjured patient was assessed and did not require transport to hospital.
Police are appealing for anyone with information, CCTV or dashcam footage.
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