Two men were killed in separate crashes in Co Cork and Co Clare in the early hours of Tuesday.
In the first incident, a man in his 30s died after being struck by a vehicle on the N25 near Cobh Cross, Tullagreine, Carrigtwohill, at around 1.50am.
A Garda spokesman said: "The vehicle involved failed to remain at the scene.
"There is no description of the vehicle at this time. However, initial inquiries indicate it may have been travelling westbound on the N25 at the time of the collision.
"The scene is currently preserved for a technical examination and local diversions are in place."
Gardaí have issued an appeal for anyone who travelled in the area between 1.30am and 2.30am and may have dashcam footage to contact Midleton Garda station on 021 462 1550 or the Garda Confidential Line on 1800 666 111.
Just over an hour later, an 18-year-old died in a crash in Co Clare.
The single-vehicle collision happened in the Cratloekeel area of Cratloe, Co Clare, at approximately 2.55am.
The teenager was pronounced dead at the scene.
Gardaí are appealing for anyone with information, particularly road users who travelled in the area who may have dashcam footage, to contact Henry Street Garda station on 061 212 400 or the Garda Confidential Line.
