Two boys, believed to be around 10 years old, were with a youth who produced a knife during an attempted street robbery in Sheffield.
Police officers investigating the incident in Parson Cross said the boys were with an older boy, thought to be around 17, when he threatened an 18-year-old woman with a knife in a bid to steal her bike.
The would-be robber struck in Buchanan Drive at 12.50pm on Saturday.
He was white, had dark hair and was stocky on top with a slimmer lower half. He was wearing a grey jumper, blue jeans and black trainers.
A South Yorkshire Police spokesman said: "An 18-year old -emale was on her bike on Buchanan Drive on Saturday at 12.50 pm when she was approached by a male who produced a seven inch knife and demanded her bike.
"He was with two other males described as being around 10 years old.
"The male left empty handed towards Deerlands Avenue."
Anyone with information should call South Yorkshire Police on 101.