The delivery driver, a 21-year-old man, was travelling in his van along Tickhill Road, Maltby.
Police said he noticed he was being followed by a blue Ford Transit van, which flashed its lights and was trying to get him to pull over, as though something was wrong with his vehicle.
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The driver is understood to have pulled over into a layby on Tickhill Road, close to the old Maltby Colliery, where he was then assaulted by three men in balaclavas who got out of the blue van.
He suffered minor injuries.
The three suspects stole the contents of the delivery van, before driving off in the blue van away from the scene.
Anyone with any information should call police on 101, quoting incident number 120 of September 9.
Alternatively, call Crimestoppers, anonymously, on 0800 555 111.