The victim, who was saved after a passer by disturbed her attackers, later realised she was bleeding and had what police said "looks like a slash wound" to her leg.
South Yorkshire Police said the injury "may have been caused by a knife".
The incident happened in a park off Gleadless Road in Sheffield on May 1 at around 5.30pm.
A statement from the police said: "The victim was riding her electric scooter through the park when it is reported that three men wearing hoodies pushed her to the floor. The three men were then disturbed by a passer-by and ran off.
"Officers are now appealing for anyone with information, or who may have been in the area at the time and saw or heard anything suspicious to come forward."
Anyone with information is asked to contact the police on 101, quoting incident number 684 of May 1. Alternatively, contact Crimestoppers anonymously on 0800 555 111.