Motorists are being advised to avoid the N22 after a vehicle flipped onto its side at Brennan's Glen near Killarney.
No serious injuries have been reported.
Gardaí are at the scene directing traffic, and are currently attempting to clear the vehicle.
Long delays can be expected on the N22 as traffic is down to one lane, a stop and go system is in place.
Gardaí are asking motorists to take alternative routes.