"A man was swinging a bladed weapon and attempted to cut another man" outside Cannon House in Hitchin's Queen Street, reports to police have said.
Police officers attended the incident at around 10.45pm on Friday, March 8.
The victim, who was walking towards Asda, was uninjured.
PC Sophie Cook, who is investigating, said: "I am appealing to anyone who may have either witnessed the incident take place or have spotted anything suspicious in the area.
"If you have any information, please email me via Sophie.cook3@herts.police.uk."
You can also report information by filling out the online reporting form at herts.police.uk/report, speaking to an operator in the Force Communications Room via the online web chat at herts.police.uk/contact, or calling the non-emergency number 101.
Alternatively, you can contact Crimestoppers anonymously on 0800 555 111 or by visiting crimestoppers-uk.org.
Please quote crime reference 41/19713/24.
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