Motorists in Wiltshire are advised to take extra care on the roads today, after a foggy start on the county's roads.
Thick fog is expected to linger in west Wiltshire for the next few hours, and is expected to return again early tomorrow morning.
A number of collisions have been reported across Wiltshire this morning and police, fire and ambulance are on the scene of a serious collision between a lorry and a car on the A3102 between Silver Street, Calne, and Sandy Lane.
Wiltshire Police say the road is likely to remain closed for a number of hours.
Police have also been called to fog-related traffic incidents this morning in Devizes, Amesbury and Swindon.
Officers are keen to remind drivers that side lights are not enough in these conditions - wiith visibility less than 100m across much of Wiltshire motorists should be using their headlights.
The Highway Code states that headlights must be used when visibility is seriously reduced; generally when you cannot see for more than 100 metre (328 feet).
There is no obligation to use fog lights, but if a car is involved in an accident in reduced visibility and its fog lights weren't on, then it may be queried by an insurer.
Front and rear fog lights must also be switched off when visibility improves.
Fog can seriously affect visibility, which can deteriorate in a matter of seconds. Be extra vigilant and drive only as fast as conditions allow and maintain a greater distance between you and the car in front.
The AA’s top 10 tips for foggy driving:
• Use dipped headlights at all times along with wipers and demisters
• Familiarise yourself with your front and rear fog lights – know how to switch them on and off – and use them when appropriate
• Beware of other drivers not using headlights
• Only drive as fast as conditions allow and maintain a greater distance between you and the car in front. Follow a three-second rule
• Tailing someone's rear lights can give a false sense of security and is dangerous
• If the road has street lights on, then you probably don't need your fog lights on
• Be able to stop within the distance you can see clearly – this is particularly important on motorways and dual carriageways, as vehicles are travelling faster
• Don't accelerate to get away from a vehicle that is too close behind you
• Check your mirrors before you slow down
• At a junction with limited visibility, stop, wind down the window, and listen for traffic. When you are sure it is safe to emerge, do so positively and do not hesitate in a position that puts you directly in the path of approaching vehicles