The incident occurred around 11am at the Herblingermarkt centre parking lot, Schaffhausen cantonal police said.
The woman motorist lost control of her vehicle, which collided with five properly parked cars, police said in a statement.
A man who was in one of the parked cars had to jump to one side to avoid being injured, the statement said.
The fire brigade was called to extricate the elderly driver from her car before an ambulance took her to hospital.
Three of the damaged cars were hauled away by a salvage company, police said.
Damage was estimated at several thousand francs.
The cause of the accident was still being investigated by Schaffhausen police.