Four dead as heavy snow and freezing temperatures hit UK
Four people have died in car crashes amid heavy snow across Britain.
Three were killed in a crash in Lincolnshire and another man died after a collision in Cambridgeshire on Tuesday morning.
The Met Office said several centimetres of snow had fallen in some parts overnight, with between 3cm and 4cm in Newcastle and Northumberland.
Motorists have been warned to take extra care on the roads and drive to the snowy conditions.
There were 20 collisions within three hours on Lincolnshire's roads, including a school bus with 45 pupils on board, police said.
The children were unharmed after their bus collided with a car and veered off the road near Deeping St James.
A spokesman for Lincolnshire Police said some of the roads had "very icy conditions".
Many schools across the country were shut, including more than 200 in Wales, 131 in Kent and 62 in East Sussex.
Farnborough in Hampshire saw the lowest overnight temperature, of minus 8.9C.
Trains have also been affected by the snowfall, with cancellations and disruptions on lines across the country.
Southeastern, which operates in Kent, has cancelled dozens of trains, including several to London St Pancras, London Victoria and Cannon Street, while other companies affected included Southern, Greater Anglia and Great Northern.
British Airways has cancelled dozens of flights from Heathrow Airport, while easyJet warned disruption to its flights was expected.
Amber warnings for snow were in place for the south east and north east of England and the East Midlands until midday, while a yellow warning covering much of the country is in force until midnight.
Forecasters are predicting 5cm-10cm of snow will fall for most areas of the UK, with up to 40cm possible for higher ground in Scotland.
Met Office meteorologist Emma Sillitoe said: "There will also be further disruption throughout the day as these showers become widespread across the country."
Conditions are not likely to improve for several days, with forecasters warning that snow will continue well into the week.
Retailers said they have not seen widespread panic buying, after some shoppers reported supermarkets were busier than usual.
An amber snow warning is in place for the North East and Scotland from 6am on Wednesday to 12pm on Thursday, with up to 40cm of snow expected to fall during that period.
Forecaster Frank Saunders said parts of the country could see their "coldest spell of weather since at least 2013, and possibly since 1991".
It is expected that the mercury could plummet to minus 15C by midweek where there is snow on the ground, rivalling temperatures forecast for parts of northern Norway and Iceland.
From Thursday, forecasters predict that another weather system, Storm Emma, will bring blizzards, gales and sleet as it meets the chilly "Beast from the East" later this week.
The storm, named by the Portuguese Met Service, will move north through Europe and is due to hit the UK on Thursday and Friday, and will be "significantly disruptive", bringing the risk of power cuts and transport delays.