He had served as a Garda for 24 years.
The Garda who was shot dead in Roscommon overnight has been named as Detective Garda Colm Horkan.
The incident took place when Detective Horkan was on patrol in Castlerea when he went to deal with something on the main street.
The situation evolved into a physical altercation and he was shot dead with his own gun.
Emergency services treated him at the scene but sadly Gardaí confirmed early this morning that Detective Horkan had died. He was in his late 40s and has served as a Garda for 24 years.
A man in his 40s has been arrested and is being questioned at Castlerea Garda Station.
The Garda Commissioner Drew Harris has made a direct appeal for witnesses to come forward.
Tributes.
The Taoiseach has led tributes to him, saying his thoughts are with all those grieving as a result of the shooting.
Leo Varadkar said gardai put themselves on the frontline every day and sometimes they make the ultimate sacrifice in the course of their duties.
Meanwhile the Justice Minister says he’s shocked and saddened at the shooting, saying the garda’s heroism will never be forgotten.
Charlie Flanagan described him as a brave garda who died protecting the community.
He is survived by his parents, sister and three brothers.