One person has been rushed to hospital after the collision which happened just before 1pm at Moorefield approaching Ramelton.
Gardai, ambulance and fire service personnel rushed to the scene and a number of people had to be cut from the wreckage of the smash.
At least two of the people involved are understood to be form the Ramelton area.
Diversions are now in place and it is expected that the road will be closed for a number of hours.
It is not thought that the condition of the person taken to hospital is critical.
A source revealed “Any crash involving three cars is serious and this could have been very serious.
“It’s a miracle that nobody was killed. The road looked a right mess after it.
“The emergency services were on the scene very quickly but there will be a lot of delays on that road.
“The main thing I that nobody was fatally injured.”