Ice causes 'exceptional' number of accidents
Ice has caused treacherous conditions in West Yorkshire, with the emergency services reporting high numbers of accidents on roads and pavements.
Black ice has resulted in an "exceptional" number of crashes, mainly on the motorway network, police said.
Yorkshire Ambulance Service said it had received "unprecedented" levels of calls relating to the ice.
It urged people only to call 999 if someone had a life-threatening illness or injury.
The service said it had activated its "major incident plan" to allow special arrangements to be put in place to cope with the surge in demand, including cancelling non-essential transport journeys to help with the 999 emergency service.
Dr Alison Walker, executive medical director at the trust, said: "The service has received hundreds of 999 calls for weather-related incidents and we are treating a lot of patients involved in road traffic collisions and injured in slips, trips and falls.
"These calls are in addition to other medical emergencies such as heart attacks and strokes."
Neil Liversidge, from Great Preston near Leeds, described the pavements as "lethal" in a call to the BBC Radio Leeds breakfast programme.
He said: "I came out of the house to go to work and our drive is like the Cresta Run.
"I went down with a hell of a bang, I'm going to be walking like Max Wall all Christmas I think.
"My wife came running out before I could stop her and she did the same.
"She is in an ambulance on the way to Pinderfields Hospital: she split her head open."
West Yorkshire Police said there had been collisions on the northbound and southbound carriageways of the M1, with the southbound carriageway closed near Junction 41.
The A1 southbound carriageway near Junction 45 was closed after a crash involving two lorries and a car.
No serious injuries have been reported, police said.
Meanwhile, delays have been reported to flights arriving and departing from Leeds-Bradford International Airport.