Police blocked the A590 between the roundabout for the Askam turn off and roundabout nearest to the zoo.
An eyewitness said an unmarked police car was seen blocking the Dalton end of the road.
A spokesman for Cumbria Police said: "Police were called at around 9am to a report of a concern for safety on the A590 near Dalton.
"A woman in her 20s from Ulverston was located and left in the care of medical staff."
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