Drivers are facing two hours of tailbacks on the M25 and across the Dartford Crossing following a multi-vehicle smash which left one woman hurt.
An air ambulance was seen landing on the motorway near the A282 as National Highways warns of “severe delays”.
Kent Police and the county’s fire and rescue service are among emergency services on the scene.
They were initially called to a crash between a lorry and a van around 4pm.
A police spokesman said: “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.”
Her injuries are not thought to be life-threatening.
Motorists report being stuck in 11 miles of congestion southbound.
There is also a four-miles jam northbound, said National Highways.
Traffic is being held in both directions on A282 with congestion reaching Junction 29 of the M25.
National Highway said: “Following a multi-vehicle collision on the A282 southbound near Dartford, the M25 is closed clockwise between J30 (Purfleet-on-Thames) to the A282 southbound J2 (Dartford).
“Severe delays of two hours above usual journey times are being reported on the M25 clockwise from J29 to the A282 J2 and approx. Eleven miles of congestion.
“Delays of 60 minutes are being reported on the M25 anti-clockwise between J3 (M20, Swanley) and J1a (Dartford).”
DARTFORD: An air ambulance has landed on the A282 between J1a and J1b due to a multi-vehicle traffic collision beneath the London Road flyover. The A282 is currently closed both ways. Photo: Jason Brooks. pic.twitter.com/sSr8IvM0uo
— Kent 999s (@Kent_999s) July 24, 2024
Motorists at 7pm told of their fury after being stuck in the traffic for more than three hours with nosign of the motorway reopening
Traffic monitoring site Inrix reported earlier: “M25 in both directions blocked, severe delays due to accident and multi-vehicle accident from J1B A296 Princes Road (Dartford) to J2 A2 (Darenth Interchange).
“Congestion to J28 (A12 Brook Street Roundabout), with delays along the A13 in both directions on approach to the M25. Anticlockwise is queueing back to J3 (M20 Swanley interchange).
“Ongoing since around 4.15pm with both sides now blocked for an air ambulance to safely land.”
Kent County Council added: “UPDATE: M25 / A282 J1A - J1B Clockwise: Reports that traffic is currently held in BOTH directions on the M25 / A282 between J1A and J1b due to a multi-vehicle collision on the clockwise carriageway.
“Emergency services are in attendance, please use caution.”
