Four people have been taken to hospital after a two vehicle collision in Rocky Lane between Haywards Heath and Burgess Hill.
A collision happened just before midday today (Tuesday), according to Sussex Police.
Ambulances were sent to the scene and four casualties were taken to hospital.
A police spokesman said they were believed to be conveyed for checks but were not thought to have sustained serious injuries.
The road was closed while police and ambulance services dealt with the vehicles and casualties.
Oil spilled on to the surface was also being cleared.