Gardaí are currently at the scene of a fatal single vehicle road traffic collision involving a car that occurred between 5am and 5:30am on Saturday morning.
The sole occupant of the car involved, a man in his 30s, was pronounced dead at the scene.
The road is currently closed and is expected to remain closed for a number of hours today. Local diversions are in place. Forensic Collision Investigators have been requested at the scene.
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 R421 at Clonagh East in Tullamore between 4:45am and 5:45am are asked to make this footage available to gardaí.
Anyone with any information is asked to contact Tullamore Garda station on 057 932 7600, the Garda Confidential Line on 1800 666 111, or any Garda station.