Emergency services were called to a home in the Lofthouse area of the city this afternoon after a young boy was knocked down.
The incident happened shortly before 2.15pm today at house in Lingfield Nook Lane.
A police spokesman said: "A young boy sustained serious injuries and was pronounced deceased at the scene.
"Enquiries are continuing to establish the circumstances around this tragic incident."
Eye witnesses reported seeing numerous police vehicles as well as ambulances, rapid response vehicles and Yorkshire Air Ambulance.
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