A woman in her 50s has died in a single-vehicle crash in Co Galway, while two young men have died in a crash in Co Antrim.
The woman died after the car she was driving hit a wall near Moycullen at about 4.30am.
A man in his 50s was also in the car, but was not seriously injured.
The woman's body was taken to University Hospital Galway and a post-mortem examination is to be arranged.
Gardaí have asked witness or anyone who was on the N59 close to Moycullen Village between 4am and 5am to contact them at Salthill Garda Station on 091-514720, The Garda Confidential Line 1800-666111 or any garda station.
Meanwhile, two men have been killed in a road accident in Co Antrim.
The victims, who were both aged 24 and from England, died when the Fiat Punto car they were in collided with a tractor.
The incident happened on the Ballyconnelly Road near Cullybackey at around 8pm yesterday.
A 21-year-old man who was also in the car sustained head injuries which are not thought to be life-threatening.
The driver of the tractor was treated at the scene for injuries which are not thought to be serious.