The incident took place on Upper Commercial Street in Batley town centre just before 10am today.
A local business owner was looking out of his window when a white Volkswagen vehicle, believed to be delivering to a nearby pharmacy, struck the woman.
He said he had thought the worst and that the woman was stuck beneath the vehicle for an hour 'or more' before emergency services freed her.
"I thoughts she was dead," he said, "she didn't move for such a long time. There was no scream or screech of tyres, nothing. And then her arm moved.
"She was under there for at least and hour, up to her waist. Time seemed to move so slowly."
A woman at a nearby cafe said: "It was awful. You just go cold, don't you?
"Everything happened so quickly and then there was panic, people running around trying to help. I hope she recovers."
A Yorkshire Air Ambulance landed in the street following the incident.
Nearby roads were closed but was due to be reopened at around 11.30am.
Pictures courtesy of John Deruvo.