A 20-year-old man from Dún Laoghaire is in a critical condition in Beaumont hospital due to head injuries he received in an attack.
The man was socialising with friends on St Patrick's Day but was attacked after 3am at Corrig Avenue near the junction with Main Street, Dún Laoghaire.
Gardaí are seeking to interview a taxi driver who picked up two men at Glenageary Road Lower between 3.15am and 3.45am on Saturday. The taxi brought them to the Shanganagh Cliffs area of Shankill, and both possibly went into a house in Shankill. Anyone with information is asked to contact gardaí at Dún Laoghaire at 01-6665000.
Meanwhile, in Co Kerry a female garda had her nose broken by a woman she was trying to arrest and two other gardaí were injured as a result of an attack by a drunken group in Castleisland following St Patrick's Day celebrations.
Sgt Dermot O'Connell of Killarney Garda described the scene in Castleisland as "an appalling incident". A large number of onlookers watched as the gardaí were assaulted with "fists, kicks and head-butts" in what was an extremely violent incident.
He said an off-duty garda based in Dublin who was passing through Castleisland saw what was happening and came to the assistance of his colleagues.