KSS Air Ambulance said they were called to the incident in Chapel Road, Worthing, at 9.45am.
KSS Air Ambulance confirmed a 34-year-old woman was treated at the scene with head injuries.
She was taken to the specialist neurological unit at Royal Sussex County Hospital, Brighton, by land ambulance assisted by helicopter crew, KSS Air Ambulance said.
Police also confirmed that the woman was knocked unconscious and was treated at the scene by paramedics.
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