A section of the Springhill road near Ballindrait remains closed this afternoon following a road traffic collision there this morning.
The crash, involving a bike and a car, happened at around 9am this morning.
It's understood that the cyclist sustained serious head injuries and is currently being treated at Letterkenny University Hospital.
Gardai have confirmed that a technical examination of the scene is currently underway and the road will be closed until further notice.
Motorists are being advised to seek alternative routes.