A man in his 30s died after the car which he was driving crashed in Co Clare.
The incident, at Kilmurry McMahon, Kilrush, took place on Sunday morning.
The local coroner has been notified and a post mortem examination will take place.
The road remains closed while a technical examination is being carried out by Garda Forensic Collision Investigators, and local diversions are in place.
Any road users who may have camera or dash-cam footage, and were travelling in the area between 3am and 7am, are asked to make this footage available to investigating gardaí.
Anyone with any information is asked to contact Kilrush Garda Station on 065 908 0550, the Garda Confidential Line on 1800 666 111, or any Garda station.
Separately, two men died when their car struck another vehicle in Liscooley, Co Donegal, on Friday night.
Ryan Glenn (25), and Gordy Galbraith, who was in his 30s, who were both from Castlederg in Co Tyrone, died at the scene of the crash.
Three people from the other vehicle, a Kia Sportage, were also injured.
