Two pedestrians were killed when they here hit by a car driven by an off-duty garda.
The Garda Ombudsman is investigating the accident, which happened on the N20 at Dooradoyle on the outskirts of Limerick city shortly after midnight.
The victims, two men in their 20s, died at the scene.
The area has been preserved as forensic officers and Ombudsman's investigators examine the scene.
Elsewhere a Garda is being treated in hospital after being struck by a car in Cork.
The incident happened 5.20pm yesterday while the officer was on traffic duty in Blarney.
He sustained injuries to his leg and hip and was taken to Cork University Hospital for treatment.
A Garda spokesman said the male driver was helping officers with their inquiries.
Meanwhile a 17-year-old driver died when his car left the road and struck a fence. A male passenger received minor injuries.
The accident happened at Derryadd, Killeigh, Co Offaly, shortly after 10pm last night.
The body of the teenager, who died at the scene, was taken to Tullamore General Hospital for a post mortem examination.
Gardai said 10 people have been killed on Irish roads so far this month, compared to 15 last January.
A total of 212 road users died throughout last year.