It happened at Windmill, Knockbulloge, near Cashel, shortly before nine o'clock last night.
45-year-old Thomas O'Reilly, 46-year-old Bridget O'Reilly, and their 3-year-old grandson, Tom, died when the car they were travelling in crashed into a wall.
Bridget, Thomas and Tom O'Reilly who died following a crash in Cashel - Photo Garda Press Office
Two other passengers, a man and woman, who are both 22, are being treated for their injuries at TUH.
The man is said to have serious injuries, while the woman is being treated for less serious injuries.
Local Councillor Roger Kennedy says there's shock and disbelief at this latest tragedy on the roads:
"That's a dozen in the last month, and to grow roads a lot. So, you know it's something that's unfortunately replicated nationwide, and the number of deaths on the roads have increased, but the volume of traffic on the roads has greatly increased as well, and people need to be consistent.
