A motorcyclist was hurt after being involved in a collision with a taxi in Gomersal, near Cleckheaton.
Emergency services were called to Spen Lane at Hilltop at 10.50am on Sunday. It is understood a motorbike coming up the hill collided with a Renault Megane private hire vehicle travelling in the opposite direction.
A spokesman for West Yorkshire Police said the motorcyclist suffered a serious leg injury and was taken to hospital.
The taxi driver was thought to be shocked but unhurt.
Police closed the road while investigations were made.
A man who was out walking nearby said he heard what sounded like “an air raid siren” and as he got closer realised it was a motorbike engine. A short time later he came across the accident scene.