A section of the Ballymahon to Lanesboro road in county Longford remains closed this lunchtime.
Gardaí are appealing for witnesses to the single-vehicle crash at Derrlough to come forward.
Gardaí and emergency services attended the scene on the R392 at around 6:45pm on Wednesday evening.
One man in his 30s was airlifted to the Mater Hospital in Dublin for treatment of serious injuries.
A second man, also in his 30s, was airlifted to the Midlands Regional Hospital in Tullamore, also with serious injuries.
The road was subsquently closed for the purpose of carrying out a technical exam
Anyone who was travelling in the area at the time and has dash cam footage is being asked to come forward.
Anyone with any information is asked to contact Longford Garda Station, the Garda Confidential line or any Garda station.
