A woman has been flown to a London hospital following a multi-vehicle crash involving a lorry and a van on the M25.
Drivers heading into Kent via the QEII Bridge near Dartford are currently facing delays of up to two hours.
Traffic is being held on the M25 clockwise between junction 29 for Upminster, across the Dartford Crossing to the A282 junction 1B for Dartford.
This is to allow emergency services, including the air ambulance, to work at the scene. Traffic officers are also attending.
National Highways says the road is expected to remain closed for “some time” and those heading clockwise that are caught within the closure will be released when it is safe to do so.
Anti-clockwise traffic was held for nearly an hour to allow for the air ambulance to land but all lanes have since reopened.
However, delays of 90 minutes and seven miles of congestion still remain.
Kent Police have confirmed they were called at around 4pm.
A spokesman added: “Officers attended and one woman has been taken to a London hospital for treatment.
“There is currently heavy congestion in the area and motorists are advised to find alternative routes if possible.”
It is understood that the woman’s injuries are not life-threatening.
Motorists are being advised to plan ahead if they want to travel on the M25 near Dartford or in the surrounding area this evening.
A diversion route has been set up, with drivers being advised to follow the hollow triangle symbol on road signs and enter the ULEZ boundaries.
They will need to exit the M35 at junction 30 and at the roundabout take the third exit onto the A13 westbound towards Dagenham and London.
At the interchange with the A12/A102, drivers should bear left onto the A102 southbound towards the M25 and Dover through the Blackwall Tunnel. There is a 4.72m (15’6″) height restriction.
Follow the A102 and continue on to the A2, through Kidbrook and Danson Interchanges towards the M25.
Then they should exit the A2 at the M25 junction 2 interchange. At the roundabout take the fourth exit onto the M25 clockwise.
For vehicles affected by the ULEZ or the height restriction at Blackwall Tunnel, National Highways is advising to use the M25 anti-clockwise to travel from Kent to Essex.
Emergency services have been contacted for more information.
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