The A47 was closed for several hours in both directions at North Tuddenham, near Dereham, while emergency services dealt with a crash.
Norfolk Police tweeted at just after 1.30pm that both lanes are closed and that drivers should avoid the area.
Norfolk Police has not said what has happened, but Norfolk Fire Service said it was at the scene assisting as there are vehicles blocking the road and leaking fuel.
It took six hours to clear the road of debris after it was initially closed in the early afternoon.
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