The A505 is currently closed in both directions due to a crash near Fowlmere.
Police were called just after 3pm to reports of a collision involving a car and a lorry on the A505 near Chrishall Road.
A spokesperson for Cambs police said: "The collision caused the lorry to overturn and the car to career into a ditch. Another car has then collided with the lorry.
"Officers are currently on scene together with paramedics and firefighters and the road is currently blocked.
"Motorists are urged to avoid the area and seek alternative routes."
The ambulance service was called at 3.06pm and sent a Hazardous Area Response Team (HART), an ambulance and an ambulance officer vehicle.
One person was taken to Addenbrooke's Hospital in Cambridge for further care.
Cambridgeshire Fire and Rescue Service said the A505 is likely to be closed for a few hours while the road is cleared.
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