Motorists on the A267 near Heathfield can expect long delays for several hours, according to police.
An investigation has been launched after a serious collision between a car and a lorry on the A267 near Heathfield.
Police say the incident occurred this morning at Cross in Hand, officers say the stretch of road is likely to be closed for some time and are urging people to seek other routes.
Anyone who witnessed the collision or captured any relevant mobile, dash cam or CCTV footage is asked to contact Sussex Police on 101 or online.