Seventeen people have been injured as a coach veered off a motorway and overturned in thick fog.
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.
Injuries to the male driver and 16 adult passengers included broken bones, cuts and bruises.
Six ambulances transported the injured to John Radcliffe Hospital in Oxford.
South Central Ambulance Service said: “We 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.
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“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.”
The sliproad remains closed.
It comes as drivers were urged to be wary of fog and sub-zero weather conditions across large parts of England today.
Freezing fog has settled in many places, visibility could be down to 100 metres, and ice may develop on some roads.
The “yellow” fog warning, issued until 10am today, affects much of southern England.
But patches of freezing fog have been seen from the Midlands and the Humber to the South West.
Some airports are also being hit by the bad weather, including Heathrow which says flights in the UK and Europe are being affected. Gatwick also says some flights may be delayed.
The fog is set to lift and thin slowly and could linger into the late morning and early afternoon, particularly in the South East and East Anglia, the Met Office said.
The AA has urged “extreme caution” for those heading out on the roads, adding that extra time should be allowed, tyres properly inflated and screens adequately de-iced.
On Wednesday, a fatal pile-up on the A40 in Oxfordshire in treacherous conditions left one woman dead and many injured.