Massive traffic disruption has been caused by motorway pile-ups that has left more than 20 people injured in Co Kildare.
A fleet of ambulances are at the scene of one crash at Ballymany, outside Newbridge which involved almost two dozen cars.
Fog has also caused severe traffic disruption and another pile-up at the M7/M9 intersection.
HSE spokeswoman Dympna Bracken said a major emergency plan has been put into operation at Naas General Hospital to deal with some of the injured.
“The first four patients have arrived at the hospital, three walking wounded and one injured.
“Ambulances from Dublin, Kildare, Navan, Portlaoise and Tullamore are currently at the scene of the accidents in the area.”
AA Roadwatch is advising motorists to divert off the M7 at Monasterevin, Kildare or Newbridge to avoid the long tailbacks from Monasterevin to past the Newbridge exit.
Motorists should slow down to at least 30km/h northbound and southbound and turn on hazard lights.
Fog is also extremely dense throughout the area from Portlaoise through to Naas.