Two people were killed in separate road traffic incidents in Dublin and Mayo on Monday afternoon.
The deaths brings to six the number of road fatalities on the island of Ireland in just over 24 hours.
A man in his 80s has died after the bicycle he was riding collided with a car in Ballyfermot, Dublin 10, on Monday afternoon.
The incident occurred on Killeen Road shortly before 1pm. The cyclist was later pronounced dead at the scene.
His body was taken to Dublin City Morgue where a postmortem will take place.
The driver of the car was unharmed, said gardaí who are appealing for any witnesses to this collision, including those who may have dash-cam footage.
Anyone with information is asked to contact Ballyfermot Garda station on 01-6667200, Garda Confidential Line on 1800-666111, or any Garda station.
In Co Mayo, a man died following a two car collision on Monday evening.
The deceased was a passenger in one of the vehicles.
The crash occurred around 5.35 pm at the entrance to Breaffy House Hotel on the Castlebar to Balla Road.
A number of other occupants in the crash vehicles were injured.
Their injuries have been described as not life-threatening.
The Castlebar to Claremorris road was closed to traffic on Monday evening pending a forensic investigation of the scene.
Gardaí are appealing for witnesses
In Co Tyrone, three men died following a two-vehicle crash early on Monday morning.
The crash happened at around 1.50am at the Omagh Road area of Garvaghy and involved a car and a lorry.
The three men, all aged in their 20s, died at the scene. A fourth man, also in his 20s, was being treated for serious injuries in hospital on Monday evening.
On Sunday evening, a young man was killed and a woman seriously injured in a road traffic collision in Co Wexford.
The man, aged in his early 20s, was the driver and sole occupant of the first vehicle and was killed in the crash.
The driver of the other vehicle, a woman in her mid-50s, was seriously injured and was taken to St Vincent’s Hospital, Dublin, in a critical condition.
The collision took place at about 5.20pm on Sunday at Ballintore, Ferns, Co Wexford.