The crash happened at around 4.10pm on the Chelmsford-bound carriageway between the M25 / Brook Street junction and J12 for the Mountnessing and Shenfield turn-off.
Fire crews are on the scene and they are dealing with a fuel leak and the road is partially blocked.
It is understood that five people have been hurt in the crash, but it is not known how badly.
There is traffic queueing back onto the M25.
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