Gardaí are investigating the death of a 20-year-old man in Naas, Co Kildare, last night.
A number of youths became involved in an altercation with another man at Harbour View at around 10.20pm last night.
A 20-year-old man received head injuries. He was taken to Naas Hospital where he was pronounced dead shortly afterwards.
The area has been sealed off while gardaí carry out a technical examination of the scene.
The office of the State Pathologist has been notified and a post mortem examination will be carried out later.
A 42-year-old man was arrested at the scene and he is being held at Naas Garda station.