Diversions are in place to allow emergency services to deal with the crash on the A66 at Threlkeld, near Keswick.
Travelling towards west Cumbria, motorists are advised to use junction 41 of the M6, travelling along the B5305, Wigton.
Travelling towards Penrith, motorists should follow the diversions in place at the Crossthwaite roundabout, Keswick.
Cumbria Police say that the road will be closed for some time.
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Kerrie Gosney brings you Sunday night's forecast
The party leader said her MPs may be in a position to act as deal makers - and they would refuse to allow an exit from the EU.
Rain spreading east Sunday. Decent day on Monday, more changeable thereafter