A Donegal man (30) became the fourth person killed on Ireland's roads after an early morning crash in Carrigans, Donegal.
The man was a passenger in a car that struck a wall. No other vehicle was involved.
The male driver, who was seriously injured in the collision, was taken to Altnagelvin Hospital, Derry, for treatment.
A total of 24 people have died on the country's roads this month after four people were killed in a series of accidents over the weekend.
A woman, thought to be in her 50s, died after a car accident in Ennis, Co Clare, yesterday afternoon.
The woman, who was a passenger in the car, was taken to Ennis hospital after the car struck a wall but she died from her injuries.
On Saturday two men were killed after two cars collided on the main N11 road in Co Wicklow.
The crash happened at Scratnagh Cross, five miles north of the town of Arklow and the road was closed for a number of hours.
It is understood that the driver of one of the cars and a passenger from the second vehicle died in the accident.