Emergency services, including the Air Ambulance, were called to Tollagte Hill, near Pease Pottage, just after 11am this morning (November 14).
The ambulance service said paramedics along with the HART specialist response team rushed to the scene and helped treat a man and a woman who were struck by the trailer.
They suffered multiple injuries and were rushed to hospital for further checks. Their injuries are not thought to be life threatening, police said.
The road was closed at the junction with William Morris Way.