The ambulance service was called to the scene and the man has been taken to hospital with serious injuries.
There are currently two scene watches in Market Square and Candleford Court.
We are appealing to anyone with information, any witnesses, or anyone with footage in or around Market Square and Candleford Court to contact the force as soon as possible.
You can leave any information on our website or call 101, quoting reference number 1981 (27/11).
Alternatively, you can contact Crimestoppers anonymously on 0800 555 111.
At this stage of the investigation, we do not believe this incident is connected to the recent violent offences in Chandos Park in the town.