The single vehicle collision occurred at approximately 11.30pm on the N80 at Leagh on the Wexford Road, County Carlow.
Kiltegan's Daryl Culbert, Michael Kelly and Katie Graham all died when the car hit a tree and burst into flames.
A man in his 20s, continues to receive medical treatment at The Mater Hospital in Dublin.
Garda Family Liaison Officers have been appointed and continue to provide ongoing support to the families.
An incident room has been established at Carlow Garda Station.
Gardaí are appealing for any witnesses to this collision to come forward.
Any road users who may have camera footage (including dash-cam) and were travelling on the N80 (Carlow town to Bunclody road) at Leagh, or the surrounding areas, between 11:15pm and midnight on Wednesday, 31st January, are asked to make this footage available to Gardaí.
Anyone with any information in relation to this collision is asked to contact Carlow Garda Station on 059 913 6620, the Garda Confidential Line 1800 666 111, or any Garda station.