One line of inquiry is that a row broke out at the farm near Kanturk over land and inheritance.
Post mortem exams are underway on the bodies of the three men - father Tadgh and sons Mark and Diarmuid O'Sullivan - as gardai try to piece together what happened yesterday morning.
It appears the older brother 26 year old Mark had been shot first in a bedroom in the house and his death is being investigated as a murder.
Mark’s mother Ann fled the scene and raised the alarm.
When gardai finally gained entry to the farm, they found the body of Mark’s younger brother 23 year old Diarmuid and their father Tadhg about half kilometre away in a field. They had also died from gunshot wounds
Speaking to RedFM News local Cllr Pat Hayes says he believes the community will pull together:
