The incident involving a black Peugeot and a pedestrian occurred at around 1pm today (Wednesday 22 June 2011).
The vehicle did not stop at the scene and urgent enquiries are being conducted to trace the driver.
The male pedestrian suffered serious head injuries in the collision and is being treated at the scene by paramedics.
The road is closed between Skipton Road roundabout and Airedale roundabout as emergency services deal with the incident.
Any witnesses to the collision are urged to contact North Yorkshire Police on 0845 60 60 24 7, quoting reference number NYP-22062011-0204.
Further updates to follow.