Garda Commissioner Drew Harris has described the murder of Detective Garda Colm Horkan as a random act.
The 49 year old was on patrol in Castlerea, Co. Roscommon when he stopped a man who was creating a disturbance shortly before midnight.
A physical altercation broke out, during which the man took Garda Horkan's gun.
He was shot a number of times and died at the scene.
Commissioner Harris says an act like this impacts the whole of society.