A "serious" crash on the N40 link road near Mahon Point is causing traffic jams in the area.
According to Gardaí the incident involved a truck and three cars and was "quite serious."
It is not yet known if there are any injuries as an assessment is still being carried out, but a Garda source said it was "likely."
Ambulance, fire services and Gardaí are at the scene and the road has been reduced to one lane heading west on the N40, out of the Jack Lynch tunnel.
On the scene, witnesses say both sides of the N40 is caught in traffic jams.