Three men died in a six-car collision on the M50 motorway near the Finglas turnoff last night.
The crash, which occurred on the southbound route shortly before 10 p.m., brought to eight the number killed on the roads yesterday.
Dublin Fire Brigade said two men, aged 19 and 25, died at the scene and a third on the way to hospital. A woman who suffered minor injuries was taken to James Connolly Memorial Hospital.
Emergency services closed a section of the M50 southbound between the Ballymun and Blanchardstown intersections as they attempted to clear the roadway. The route remained sealed off early this morning.
Earlier a man in his 40s died when his car crashed into a railway bridge at Knockwilliam, Ballyhale, Co Kilkenny. The accident occurred at around 8 p.m. In east Cork, two men were killed and three others injured in a car crash early yesterday morning.
The accident happened at Burgess Cross between Killeagh and Youghal at 7.30 a.m. The black Fiat Punto in which the five people were travelling went out of control and hit a wall. The car fell about five feet into a drain.
The driver and one of the rear-seat passengers died instantly. The driver was named as Mr Wayne Martin (21), of Ardcullen Estate, Hollyhill, Cork city. Mr Cian O'Mahony (19), of Dromdiah, Killeagh, Co Cork, was the other fatality.
Gardai and the emergency services were on the scene within minutes.
The three injured passengers were taken to Cork University Hospital.
Two of the surviving passengers are described as being in a serious condition. The other passenger escaped with minor injuries.
Gardai say no other vehicle was involved. The road was said to be wet when the accident happened.
Earlier, at 12.40 a.m., a man in his 30s died when his motorcycle was in a collision with a car at Temple Villas, Rathmines, Dublin. A 22-year-old man died in Belfast when a Renault Clio in which he was a front-seat passenger crashed on College Avenue, in the Millfield area of the city, around 3.30 a.m. He was named as Mr Stephen Hughes from Old Coach Road, Upper Malone, Belfast. No other vehicle was involved and the driver was brought to hospital. Road accidents have claimed 81 lives in the Republic since January 1st, according to Garda figures.