Officers are hunting a man who is said to have attempted to force a pregnant woman into a car in the early hours of Sunday morning.
The 41-year-old woman was walking along Oswald Road at around 3am, when a man in a black saloon car slowed and asked if she was okay.
She replied she was, but he continued to follow her, repeating the question.
It is then said he got out of the car and grabbed her by the hand, before trying to force her into the car.
She managed to escape and he drove off in the direction of Frodingham Road.
He is described as white, well built, aged 30 to 35, around 6ft tall, with a shaved head and local accent. He wore a white and blue T-shirt.
Anyone with information is asked to call 101, quoting crime number 131 of Sunday July 12.