Police are appealing for witnesses after a five vehicle collision involving a tractor in Stoke Ash.
Officers were called on Saturday to the A140, near to the White Horse Inn pub, shortly before 9.30pm. Suffolk Fire and Rescue and the Ambulance Service also attended.
A yellow tractor pulling an empty trailer collided with four cars. A grey VW Golf involved in the collision, then collided with a tree.
The male driver of the tractor sustained a puncture wound to the back and bruising, and the female passenger sustained bruising.
The male driver of a grey VW Golf sustained a fractured collar bone and whiplash, and the female passenger sustained serious injuries of a fractured femur, head injury and abdominal injury. The woman was taken to Addenbrookes, where she currently remains in a serious condition.
The male driver of a black Audi A7, the female driver of a silver Mini Cooper and the female driver of a grey Honda Civic all sustained minor injuries, along with other passengers in the vehicles.
The road was closed whilst an investigation took place and was re-opened around 9am on Sunday 30 August.
Anyone who witnessed the incident or saw any of the vehicles being driven before the collision is asked to contact PC John Clarke Roads Policing and Firearms Operations Unit at Suffolk Police on 101 quoting CAD 436 of 29/08/15.