Police and firefighters are at the scene of an incident on the A14 at Nacton near Ipswich, close to the Orwell Bridge.
Emergency services were called at around 2pm to reports of a car on fire.
A police spokesman said smoke can be seen coming from the vehicle but it is not actually alight.
It is blocking one lane of the A14 westbound and traffic is building behind it.
No-one is thought to be injured and ambulance crews have not been called, the police spokesman added.
Two people inside the car managed to get out quickly and police are assisting at the scene.
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