Two masked raiders armed with a sledgehammer and adjustable wrench tried to smash their way into a wine shop during the early hours of the morning.
Armed police rushed to Village Wines in Miswell Lane, Tring, just after midnight on Monday.
When the crooks were challenged by nearby neighbours they turned their weapons onto one of the men, hitting him several times on the head and body. Luckily the victim was not seriously injured but has been left badly shaken by the ordeal.
Det Sgt Craig Flint, who is leading the investigation, said: “This was an aggressive crime which saw these people force their way into a premises before assaulting a member of the public who tried to intervene.
“They showed no mercy as they assaulted the victim who has been left in an extremely shaken state. I would urge anyone who may have noticed anything suspicious in or around the area at the time of the incident or who may have seen a dark coloured vehicle driving at speed away from Tring after the incident to contact us immediately.”
Anyone with information is asked to get in touch by calling the non-emergency number 101 and quoting crime reference D3-13-43.