The youngster was walking with his mum along Stradbroke Drive, Stradbroke, when he stepped into the road and was struck by an on-coming car.
Emergency services were alerted to the incident just before 6.30pm yesterday.
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Police officers investigating the incident want to speak to driver of the car involved.
The motorist, who was in a blue or a black car, is said to have ‘expressed concern’ and is not believed to have been driving ‘inappropriately or dangerously’.
Officers are urging the driver and any witnesses to come forward.
Call South Yorkshire Police on 101 and quote incident number 849 of July 16.