Police rushed to Hemel Hempstead’s town centre after a fight broke out on Saturday.
The altercation just before 6pm in Marlowes is believed to have involved a group of teens, with one reported to have been wielding a metal bar, who set upon a male victim.
But when officers arrived at the scene, both the group and the victim had made off. A Herts Police spokesman said: “No one has made themselves known and no offences have been reported.”