Traffic is increasing as traffic officers rush to the scene of the collision.
The crash occurred between intersection 24 of Potters Bar and intersection 25 of Cheshunt on the M25.
Traffic was stopped counterclockwise on the Hertfordshire section of the motorway.
Then only one lane of the roadway was allowed to pass through.
Highways England warned drivers of delays, providing a later update on traffic flow and remaining congestion.
“However, 3 lanes (out of 4) remain closed at this time.
“There’s just over a mile of congestion approaching, but it’s likely to increase rapidly.”
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