Rod Allday/GeographA man was threatened with a small sword at a busy shopping centre.
Essex Police was called to The Water Gardens in Harlow just after 16:10 BST on Wednesday.
It said a group of people threatened the man but he did was not suffer any injuries.
No arrests have been been made and police are following “a number of targeted lines of enquiry”.
Det Insp Karen Knibbs, of Harlow CID, said: “We know this incident took place in public and will have shocked those who saw it.
“I’d like to thank the members of the public who alerted us, which meant officers were able to respond within a matter of minutes.
“Anyone who witnessed the incident or any behaviour in the lead up to it should get in contact with us as soon as possible.”