The air ambulance was called to a serious collision on the A12 northbound the Copdock Interchange on Sunday evening.
Emergency services were called to the collision just before 9.30pm on Sunday.
The road remained closed northbound between J32B and J33 at 11.30pm while the incident was dealt with.
A spokesman for Suffolk police said that two cars had been involved in the collision.
The southbound side of the carriageway was also closed while the air ambulance landed to help treat one person who had been travelling in the cars.
It is unclear at this time as to the nature of this injury.
A number of cars were believed to be stuck within the closed area of the road.
Highways England said on Twitter that those stuck should wait instruction from Norfolk and Suffolk Roads and Armed Policing before moving their vehicle.
A diversion was put in place for motorists while the road was closed.
Drivers were advised to exit the A12 at J32B and follow the B1113 through Copdock and Washbrook to the roundabout with the A1071.
Take the 3rd exit and follow A1071 to junction with the A1214 then turn right and follow A1214 to Copdock Mill.
Suffolk Fire and Rescue are also at the scene of the collision with four appliances attending from Ipswich East, Princes Street, Holbrook and Framlingham.
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