Six people died in road accidents in the Republic and the North at the weekend, three of them in a single, head-on crash in Co Monaghan on Saturday morning.
The weekend fatalities also included an elderly couple whose car crashed into a fallen tree as they were on their way to Mass in Co Fermanagh early yesterday.
Saturday's fatal collision occurred at 3.30 a.m. at Tullyvaragh, four miles north of Carrickmacross on the Main N2 Dublin/Derry road.
Killed in the crash were the two occupants of a Renault 19 travelling towards Castleblayney, and the driver of a Nissan Primera travelling towards Carrickmacross on the straight stretch of road.
The occupants of the Renault were named as Ms Angela Woods (42), a mother of six from Drummond Etra, Carrickmacross, and Mr Michael McGeough (36), of Main Street, Carrickmacross.
The driver of the second car was named as Mr Chris Cumiskey (21), of Lurgan, Cullenboy, Silverbridge, Co Armagh.
Two units of Carrickmacross fire brigade attended the scene.
The road was closed for almost eight hours, and diversions put in place as Garda technical experts made a detailed examination of the scene.
Insp Jim Marks, of Carrickmacross Garda, said: "We would like to offer our sincere sympathy to the families of the deceased persons in this tragic accident.
"We are now appealing for witnesses using this stretch of road between 3 a.m. and 3.30 a.m. to come forward with any information which might help us in our enquiries."
Carrickmacross gardaí can be contacted at (042) 9661222 or (042) 9661560.
Meanwhile, gardaí in Co Kildare are investigating a fatal crash on the Rathangan to Edenderry road shortly after 2 p.m. on Saturday.
A 23-year-old man was killed when his motorcycle was in collision with a car.
No one else was injured in the crash.
In Co Fermanagh yesterday, an elderly married couple died when the car in which they were travelling hit a fallen tree on the Derrygonnelly road at Killyveagh, six miles from Enniskillen.
Mr Joe Leonard (74), who was driving, and his wife, Una (68), had been on their way to 9 a.m. Mass in Monery where the collision occurred.