The incident happened on the main Letterkenny to Derry road.
Traffic diversions have already been put in place and lengthy delays are expected in the area for at least the next few hours or so.
It is not yet known how seriously injured those involved in the accident are.
Gardaí are still at the scene surveying the incident, while those injured have been removed from the scene to Letterkenny General Hospital via ambulance.
We’ll have more on this story as it emerges.