Gardaí are investigating two separate incidents in which two teenage boys and a woman died as a result of road crashes Cork and Dublin.
Gardaí in Gurranabraher, Cork are investigating a crash at Harbour View Road, Knocknaheeney, at 11.35pm last night.
A 16-year-old boy was injured when the car in which he was a back seat passenger was involved in a collision with another car and hit a wall.
The boy and the four other occupants of the car were taken to Cork University Hospital where he was later pronounced dead, a Garda spokesman said.
A second teenager died in hospital this morning. The three injured people are in said to be in a stable condition.
Neither of the two occupants of the other car was injured.
Anyone who may have witnessed the incident is asked to contact Gurranabraher Garda station.
A Garda spokesman said two men - aged 40 and 21 - were arrested in relation to the crash. They are being held at Gurranabraher.
Separately, a 44-year-old woman was injured when she was hit by a car on the city-bound lane of the N4 near Lucan in Dublin shortly after 11pm.
She was taken to Connolly Hospital in Blanchardstown where she was pronounced dead shortly before 2am.
A Garda spokesman said no one else was injured in the incident.
Gardaí at Lucan are seeking witnesses.