A 23-year-old woman who died in a suspected murder-suicide in an outback town was pregnant at the time of her death, police have confirmed.

Multiple residential blocks in 3000-person town of Charleville – located about 740 kilometres west of Brisbane – were placed into lockdown for almost eight hours on Wednesday night following reports of a serious assault.

A second-year constable rescued an 18-month-old girl from the scene, but officers who later entered the house found the bodies of a 45-year-old man and a 23-year-old woman.

In an update on Friday, Assistant Commissioner Matthew Vanderbyl said police had confirmed the 23-year-old woman was pregnant when she died.

He said the young woman and 45-year-old man had been a couple, but said officers were still determining the paternity of the unborn child.

Police established a crime scene on Thursday, and were treating the deaths as a murder-suicide.

The toddler – who had been covered in blood – was taken to hospital, but was not seriously injured.

Vanderbyl said the officer held the initially distressed child close to his chest and away from police operations until she calmed down and could be treated.

“You have to feel for a child who has potentially seen what she has seen at that scene,” he said.

“We follow processes and procedures … but there are also situations in policing where humanity kicks in.”

Earlier on Thursday, Vanderbyl said negotiators and later specialist police from Brisbane had arrived during the siege.

“It will take some time to try and piece together the events of what happened last night,” Vanderbyl said.

On Friday, the assistant commissioner said police would stay at the house over the weekend examining the “incredibly confronting, traumatic, and tragic crime scene”.

“Due to the state of the scene, and the nature of the house … we haven’t completed the search of the scene as yet,” he said.

Police were yet to find a gun inside the home, but Vanderbyl said threats were made to officers and negotiators on Wednesday night, prompting a “tactical withdrawal”.

“They were in what I would consider was grave danger … but whether firearms or other weapons are involved will probably likely be confirmed early next week,” he said.

Vanderbyl said a postmortem examination was scheduled in Brisbane next week. Until then, he could not provide details on how the pair may have died, or the nature of their injuries.

The assistant commissioner said the man was on the phone to someone while officers were outside the home, but would not be drawn on the other party’s identity.

The assistant commissioner thanked the Charleville community for supporting police and those close to the deceased, and said the Child Safety Department was involved in the toddler’s care.

The case would be investigated by the Ethical Standards Command, as the pair died during an active police operation, Vanderbyl said.

If you, or someone you know, needs support you can call Lifeline on 13 11 14 or Beyond Blue on 1300 224 636.

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