This is the scene on the A66 at Threlkeld in the Lake District, where two vehicles collided.
Two adults and a boy aged 10 are seriously ill.
Two other children have also been taken to hospital.
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A number of roadwork projects in Cumbria will be temporarily lifted over the Bank Holiday Weekend, to make travel easier.
There will be major delays to almost all railway services in the region over the three days. Replacement buses will be operating.
Police and local authorities in Cumbria are issuing road traffic and safety advice ahead of the Appleby Horse Fair, which begins next week.