About 500 people are stranded on Bodmin Moor in Cornwall following a crash which has closed a snow-hit road.
More than 100 cars and coaches are on the blocked road, following the crash, which involved dozens of vehicles.
Military helicopters have been called in to help police deal with what they are calling a major incident, following England's first snow of the winter.
There have also been snowfalls in Devon, Dorset, Somerset, North Yorkshire and East Anglia.
In the Bodmin incident, the vehicles are stuck on the A30 road between Kennards House and Bodmin, near Jamaica Inn.
The snow has also brought Newquay airport to a halt, with staff saying the runway was closed to all air traffic.
In Devon, there were reports of snow up to eight inches (20cm) deep with road conditions hazardous and police warning people to only make journeys "if extremely necessary and in an appropriate vehicle".
Several crashes were reported in Dorset with a coach carrying 29 children stuck in the snow at Lyme Regis.
About two inches (5cm) of snow fell on the North Yorkshire Coast and North York Moors with more roads blocked.
Snowploughs were called out to help clear roads in Dorset, with the worst hit areas around Lyme Regis, Bridport and Charmouth.
A Dorset Police spokesman said: "The roads are absolutely treacherous and conditions are very bad. Vehicles are having difficulty getting up the hills."
Snowfalls in Somerset saw thousands of school pupils told to stay at home with more than a dozen schools closed across the county.
The Met Office issued a severe weather warning, predicting heavy snow and blizzards for several regions, while the Highways Agency advised drivers to prepare themselves and their cars and to slow down on roads.