Heavy snowfall is hitting parts of the UK, causing road and rail disruption.
Police say driving conditions are "treacherous" in places as a band of wintry weather and very low temperatures sweeps westwards.
Hundreds of trains are cancelled, many schools are shut and forecasters say some rural communities may be cut off.
Kent, Surrey, Suffolk and Sussex are among the worst-hit counties, seeing up to 10cm of snow, while north-east England has received up to 8cm (3in).
Amber Met Office weather warnings are in place in those areas, meaning there is a possible risk to life and property.
A less severe yellow warning applies to a much wider area, covering much of Scotland, England and Wales.
In Lincolnshire, police helped 45 schoolchildren from their bus after it collided with a car and left the road. None of the pupils were injured, but the force said conditions were "particularly hazardous".
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The UK is experiencing what's expected to be the coldest week of the winter, with snow moving west during Tuesday, increasingly spreading into Scotland and the Midlands later in the day.
Temperatures dropped well below freezing overnight, with Northern Ireland, south west England and East Anglia logging figures as low as -6C. Altnaharra in the Highlands recorded -8.5C.