A man armed with a hunting knife stole the mobile phones from three men sat in a car in Rotherham.
The victims were in Wharton Avenue, Swallownest, when they were approached by the robber.
He was mixed race, aged between 18 and 29-years-old and around 5ft 8ins tall.
The man was of a medium build, had a scruffy stubble beard and was wearing a black hooded puffa jacket and a black beanie hat.
Anyone with information should call 101.