A woman who was among three people killed at a home near Toowoomba, west of Brisbane, was heavily pregnant, police say.

The bodies of a 52-year-old man, his 27-year-old daughter Kris-Deann Sharpley and seven-year-old grandson Jackson were found on Monday night by a relative who also lived at the house in the township of Biddeston, 25 kilometres west of Toowoomba.

Police said the adults were shot in the head at close range with a high-calibre gun, but no details have been released about the cause of the boy’s death.

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“As to whether it (the gun) was aimed by one of the residents of the house or someone that is attached to the family that live in the house, we don’t know,” Queensland Police Detective Inspector David Isherwood said.

Forensic teams arrived at the scene late on Monday night and remained overnight into Tuesday. The street remains cordoned off.

Det Insp Isherwood said while the bodies were found on Monday night, it was believed the shootings had occurred on Sunday.

The body of the child and his grandfather were found in a bedroom and the female was in the bathroom.

Three shots were heard by two neighbours in the small rural community about 10:30pm on Sunday.

Two came close to each other, the third was some time after, Detective Inspector Isherwood said.

When police arrived they had to force their way in.

“It would appear the house was secure,” Detective Inspector Isherwood added.

“The police that attended the scene were distressed mainly because the injuries were quite horrific, it’s a tragic event that’s occurred here.”

Pupils and teachers at boy’s school offered counselling

Meanwhile students and staff of the primary school attended by the seven-year-old boy have been offered counselling.

The education department sent professional counselling and guidance teams to Biddeston State School.

A deep sense of sadness and shock had gripped the local community after the horrific crime, regional director Greg Dickman said.

“(Counsellors) will provide support and monitor the needs of both staff and students for as long as needed,” he said in a statement.

Meanwhile, the school’s sign appears to have been changed to read “Every Day Counts” following the deaths.

Police not confirming reports of murder-suicide

Speaking to reporters, Det Insp Isherwood would not confirm whether the shooting was a murder-suicide and said officers would investigate if another person was involved.

“At this stage it does not look like that is the case, but it is too early to tell,” he said.

“I won’t disclose at this time whether it is a murder-suicide as has been alleged in the media, because we just don’t know.”

The family was known to police but a motive had not yet emerged, police said.

The neighbours that heard the gunshots did not hear a disturbance on Sunday night.

“The relatives of the people, as are the people of Biddeston, are shocked,” Det Insp Isherwood said.

“It’s a small, quiet community and for something like this to happen in a community like this would impact on the community as a whole.”

– with ABC