A man in his 20s was arrested.
A man in his 60s is in critical condition in hospital after an assault in Mayo.
The incident happened after an altercation at around1.20am on High Street in Westport.
A man in his 20s was arrested at the scene and is being held at a North West Garda Station.
The scene has been preserved for a technical examination and Gardaí are appealing for witnesses.