Three men with weapons chased another man through Swindon town centre.
CCTV images have been released as police are trying to identify the three men pictured in connection with the incident.
The suspects pursued their victim through the town centre, on to Fleming Way and to a Swindon Bus Company bus on August 27 at around 5.15pm.
The victim managed to escape by getting on the bus and shutting the door.
Fleeing the scene when officers arrived, the victim left without treatment and without reporting the incident.
There have been no reported injuries and police say enquiries are ongoing.
Two of the males pictured are riding bikes. The first is wearing a white t-shirt with a dark logo and dark tracksuit bottoms and can be seen carrying a dark object.
The second is wearing a greey hoodie with matching grey tracksuit bottoms while the third is seen with a black t-shirt and a rucksack.
In a statement, a police spokesman said: "We are aware of the impact an incident like this has on the local community, so we are urgently seeking to identify the males pictured to help us with our enquiries.
"If you can help us, please contact us on 101 quoting reference number 54220090724."