(Image: ©Archant Photographic 2010)
The busy route has been temporarily closed to allow for a helicopter from the Magpas air ambulance to land at the scene.
A man in his 30s has been treated for a serious chest injury and has been flown to Addenbrooke's Hospital in Cambridge for further treatment.
The emergency services were called to reports of a collision between a motorcyclist and a car at around 3.50pm.
The patient taken to hospital is believed to be the motorcyclist.
• More to follow
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