Bridge Street in Otley is currently closed and emergency services are at the scene.
The condition of the pedestrian is not yet known.
A West Yorkshire Police spokesperson said: "Emergency services are currently dealing with a serious road traffic collision in Otley.
"At 10.58am today (10/9) police were contacted by the ambulance service who were responding to a report of a serious road traffic collision involving a woman pedestrian and a lorry in Bridge Street, Otley.
"Emergency services are currently at the scene and road closures are in place.
"The bridge is closed to vehicle traffic and is expected to be for some time.
"Drivers are advised to avoid the area."
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