Part of the M25 is shut after a serious crash in the Holmesdale Tunnel, with drivers trapped in the road closure.
Traffic has ground to a halt on the M25 at the Essex, Hertfordshire and Enfield border following a serious collision involving two lorries.
The crash happened clockwise between junctions J25 Waltham Cross and J26 Waltham Abbey shortly after 8am near the tunnel exit.
The motorway is blocked in both directions to allow for the air ambulance to land.
The number of injuries or any casualties is not yet known, and all emergency services are at the scene.
Inrix, which analyses traffic data, said in an alert that two lorries were involved.
Drivers have been warned of 60-minute delays anticlockwise and 90-minute delays on the approach to Holmesdale Tunnel.
Queues are stretching back to J27 for M11, and diverted traffic is clogging up parts of Waltham Cross and Waltham Abbey.
Traffic on the anticlockwise lanes was released at around 10am, while the clockwise carriageway remains shut for a crash investigation.
National Highways said: ‘The #M25 clockwise is now closed between J25 #WalthamCross and J26 #WalthamAbbey #HolmesdaleTunnel following a serious collision. The anti-clockwise carriageway remains held whilst air ambulance on scene. There are approx. 5 miles congestion in both directions.’
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Traffic has also been held in the Holmesdale Tunnel.
Footage shows an air ambulance landed in the middle of the anticlockwise carriageway.
The crash comes shortly after a collision and fire further east on the M25 between Romford and Brentwood this morning, which caused long delays.
Metro has contacted the police for more information.
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