Police were alerted to the horror waiting inside a small country town home when two brothers did not show up for school.

A family and the Coonabarabran community have been left shell-shocked over the death of the six and seven-year-old, with their deaths now a double homicide investigation.

On Tuesday, those who knew the boys told how they loved karate and soccer.

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“They were two little firecrackers, just six (and) seven-years-old, full of life, energetic, involved in everything,” Coonabarabran resident Kodi Brady told 7NEWS.

The boys’ 66-year-old maternal grandmother, their sole carer, is currently under police guard in a mental health facility and is expected to be charged with two counts of murder when she is discharged.

Brady said the boys were “always with their grandmother” and they had always appeared to be a “beautiful” family.

Police say they moved to the town from the Central Coast 11 months ago.

Police forced entry to the home where they found the boys unresponsive in separate rooms.

Detectives believe they were suffocated.

The grandmother had self-inflicted injuries and was taken into custody, authorities said.

“She spoke to police about what had taken place and what had occurred in the house at that time,” Assistant Commissioner Andrew Holland told reporters on Tuesday.

“That information is being included in the investigative process.”

The children’s parents have been told.

The boys’ grandmother does not have a criminal record but had complained about depression in the past.

She was transferred to a mental health facility in Orange “where she will be detained for the near future until she improves”.

“Upon release she will then be handed back to police custody where it is likely she will face serious charges,” Holland said.

Police will remain at the home until Wednesday as they complete their forensic examination.

They will learn more about the tragedy when the post mortems are carried out on Thursday.