A 37-year-old man has been arrested and is being detained at Ballina Garda Station in relation to an alleged serious assault at Ardnaree.
A 26-year-old male sustained serious head injuries in the alleged assault at 2 am this morning.
He was brought to Mayo General Hospital and has since been transferred to the Beaumont Hospital, Dublin.
Gardaí are appealing to anyone who was in the area at the time, or anyone who has any information in relation to the incident, to contact Ballina Garda Station at (096 ) 21422.
