Dublin and Monaghan bombings
A series of co-ordinated bombings were carried out in Dublin and Monaghan, Ireland, by the Ulster Volunteer Force (UVF) on 17 May 1974. Three car bombs exploded in Dublin during the evening rush hour and a fourth exploded in Monaghan almost ninety minutes later.
Source: Wikipedia — Dublin and Monaghan bombings (CC BY-SA 4.0)