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A motorcyclist in his 60s is in a critical condition following a serious crash on Bank Holiday Monday.
The crash happened shortly after 9.30am on Monday near to the slip road towards Tonbridge and the junction with the A26. Three motorcycles were involved.
It coincided with hundreds of bikers heading towards the coast for their annual May Day Run to the Hastings 1066 motorbike event.
The motorcyclist, a man from the Maidstone area, was taken to a London hospital with serious injuries. His condition is described as being critical but stable.
Both London and coastbound carriageways were shut by police to allow the Air Ambulance helicopter to land.
A spokesman for the South East Coast Ambulance Trust said: "We sent two ambulances and a response car to attend. The air ambulance also attended.
"Our crews treated a single patient, an adult male, at the scene for serious injuries.
"He was then taken by air ambulance to King's College Hospital, London."
Highways England set up a number of diversions but many motorists were still left stranded on the A21 Tonbridge Bypass between the A26 Quarry Hill Road and A26 Woodgate Way.
The London-bound carriageway was opened shortly before 1pm and the coastbound section was reopened at around 2.15pm.
Officers from the Serious Collision Investigation Unit are investigating the incident and are appealing for witnesses who may have seen the bikes involved in the moments before the collision or anyone who has dashcam footage to come forward.
If you can help, please call the appeal line on 01622 798535 quoting AW/JG/52/19. Alternatively email sciu.td@kent.pnn.police.uk
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