The incident is still on-going and closed off Ford Road, in both directions.
It is understood the accident took place at the level crossing of the railway station.
Rail services across the Brighton-Portsmouth and the Arun Valley lines are still facing disruptions.
A spokesman for railway operators Southern, said: “Owing to emergency services dealing with an incident at Ford all service between Brighton/Arundel/Littlehampton and Barnham are subject to short notice alterations, cancellations and delays of up to 30 minutes.
“Stagecoach will pass tickets on route 700 between Brighton and Portsmouth.”
Updates to follow.