All three lanes near to junction nine of the northbound side of the motorway, near Gatwick Airport, are closed today (Saturday, March 26).
Sussex Police said it is 'not yet clear' when the road will fully reopen.
Following the collision — which happened after a police chase — a 23-year-old woman has been arrested on suspicion of driving under the influence of drugs, driving without a licence and driving without insurance.
Scroll down and click through to see pictures from the scene.
Anyone who witnessed the collision or has dashcam footage is asked to email [email protected] or call 101 quoting serial number 223 of 26/03.
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M23 closed after multi-vehicle collision. Photo: Eddie Mitchell
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M23 closed after multi-vehicle collision. Photo: Eddie Mitchell
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M23 closed after multi-vehicle collision. Photo: Eddie Mitchell
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M23 closed after multi-vehicle collision. Photo: Eddie Mitchell