A man and two women have died after their car hit a road sign on the Rathdowney to Abbeyleix Road in Co Laois.
The incident happened at 3am at Middlemount, about 5km outside Rathdowney.
The driver of the car, a 20-year-old man, was killed along with two female passengers aged 20 and 35. Their bodies have been taken to the mortuary at Portlaoise Hospital.
A 16-year-old boy who was also in the car was injured and he was taken to Tullamore General Hospital where his injuries are described as non life threatening.
The road is closed until at least lunchtime in order to facilitate an examination by Garda investigators.
Gardaí are appealing for witnesses or anyone who may have been on the Rathdowney to Abbeyleix Road between 2.30am and 3am on Sunday morning to contact Portlaoise Garda station on 057 8674100, the Garda Confidential Telephone Line 1800 666 111 or any Garda station.