Seventeen people were hurt when a coach veered off a motorway slip road and overturned in heavy fog, as poor visibility brought travel chaos to the new year getaway.
The male driver and 16 men and women passengers suffered injuries including broken bones, cuts and bruises when the Oxford Bus Company coach crashed off the northbound slip road at junction 7 of the M40 near Milton Common in Oxfordshire at 2.45am on Friday.
South Central Ambulance Service (SCAS) said thick fog had made access to the scene more difficult and Thames Valley Police (TVP) said the road would be closed for several hours.
It follows a fog warning to drivers covering swathes of England, and the crash happened 20 miles from a fatal pile-up on the A40 in Oxfordshire in similarly treacherous conditions on Wednesday morning.
An SCAS spokesman said: "South Central Ambulance Service declared this a major incident due to the number of patients involved and attended the scene with our colleagues from Thames Valley Police and Oxfordshire Fire and Rescue Service.
"There was thick fog in the area at the time of the accident which also presented challenges to the emergency services getting to the scene."
Six ambulances helped take the casualties to the John Radcliffe Hospital in Oxford.
Police are investigating and Sergeant Mark Scully, of the Hampshire and Thames Valley joint operations unit, said the fog was dense at the time of the crash.
He told Sky News: "We are lucky at the moment we are not dealing with anything considered life-threatening."
No arrests have been made, a TVP spokesman said.
An investigation into the 20-car crash on the A40, in which one woman died and many people were injured, is continuing and there have been no arrests, he added.
The blanket of fog covering the South East on Friday morning also caused cancellations and delays at major airports.
A spokesman for Heathrow said around 50 flights had been cancelled and added: "Heavy fog has been affecting flights at Heathrow today, leading to delays and some cancellations. Passengers are advised to check the status of their flight with their airline before travelling to the airport."
Gatwick also experienced delays which are expected to continue into the evening.
"Air traffic control restrictions imposed due to heavy fog across the South East and Europe are causing delays to flights to and from Gatwick as well as some cancellations," a spokesman said.
London City Airport advised passengers to check flight information in advance after the fog caused delays and cancellations to "several" flights.
Met Office forecaster Nicky Maxey said the fog would "start to ease" on Friday night, adding: "It's an improving picture so if there is fog around tonight it won't be as bad as it was last night."
But she warned that temperatures could dip below freezing by the end of the weekend.
"Sunday night into Monday we could see temperatures across most of the country hovering at freezing or just below, particularly in rural areas."
The return of the cold weather has prompted Public Health England to warn that the conditions could be deadly.
Dr Deborah Turbitt, from Public Health England London, said: "Every winter thousands of people die because of their exposure to cold weather, and doctors' surgeries, hospitals and other parts of the NHS are kept busy as people fall ill - that's why it's really important that we all do everything we can to ensure everyone stays well this winter.
"Think about how the coming cold temperatures may affect your friends, family and neighbours, particularly if they are older or very young or have pre-existing health conditions.
"These groups can be particularly at risk from the ill-effects of cold so think now what you could do to help. Keeping homes heated to at least 18C is a great way to avoid the health problems from cold, as is stocking up on food and medicine before cold weather sets in and wearing lots of thin layers instead of fewer thick ones.
"Much of this is common sense but there are people at very real risk when temperatures drop. Now is the time to think about what we can all do for ourselves and others."
Some ferry services to the Isle of Wight were cancelled due to foggy conditions in the Solent.
A Wightlink spokesman said: "Due to heavy fog and low tide the service between Lymington and Yarmouth has been suspended."
He said passengers had boarded the ferry in Yarmouth before the captain made the decision that it was not safe to travel, so they disembarked.
"We are just keeping an eye on the weather at the moment to see how soon we can actually start sailing again."
Services between Portsmouth and Fishbourne had delays of up to two and a half hours because of the restricted visibility.
Red Funnel services between Southampton and East Cowes were delayed by up to an hour.
Brighton and Hove Albion's home match against Cardiff City was called off because of the poor visibility. The club tweeted: "Match postponed due to fog: The match has been called off after consultation between match officials and both clubs."
A statement on the club's website added: "Further information, including details of the rearranged game, will be confirmed in due course."