A 58-year-old man has been arrested on suspicion of motoring offences in the early hours of Saturday.
Police are trying to establish the full circumstances surrounding incidents shortly after 3 am.
A man was found with a head injury at Halifax Police Station at 3.29 am and taken to hospital by ambulance.
Shortly before that he had been involved in a road accident at Cow Green, Halifax.
Witnesses are asked to contact police on 101.