A motorbike and a lorry were involved in a crash in Dewsbury Moor yesterday evening (Monday).
Police were called to Heckmondwike Road just before 6pm.
A police spokeswoman said the motorcyclist had left the scene before officers arrived – leaving the vehicle behind.
Officers are still looking for the motorcyclist, fearing they may be injured.
Contact police on 101 if you have any information.