A teenager is in critical condition in hospital after a serious assault in Swords, in north Dublin, on Thursday evening.
Gardaí arrived at the scene on Brookdale Avenue at around 7pm.
A 19-year-old man was reportedly transported to Beaumont Hospital, where his condition was described as critical, Garda said.
A man in his 20s has been arrested.
The scene is currently preserved for a technical examination.
Gardaí in Swords are appealing to any person who may have information in relation to this incident to contact them.
Any person with any information which may be relevant to the Garda investigation should contact Swords Garda Station on 01 666 4700, the Garda Confidential Line on 1800 666 111, or any Garda station.