Police were called to reports a pedestrian had been struck by a Ford Fiesta in Railway Road at around 7.30pm on Tuesday (November 9).
The pedestrian, a man in his 70s from Great Harwood, was taken to hospital with "serious head and shoulder injuries".
The driver of the Fiesta stopped at the scene and no arrests were made, officers said.
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PC Chris Breckell, of Lancashire Police's Tactical Operations, said: "This collision has left a man with some very serious injuries and my thoughts are with him and his family at this time.
"We are working to establish the full circumstances of the collision and I would ask any witnesses or anybody with dashcam or CCTV footage which could assist our investigation to contact the police."
Anybody with information can contact police by calling 101 or emailing [email protected], quoting log number 1360 November 9.
Information can also be submitted online at doitonline.lancashire.police.uk.
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