Thieves used concrete blocks to smash the window of a shop in Tring to steal cigarettes in the middle of the night.
The two male offenders struck at Martins newsagent on the High Street shortly after 3am on Tuesday.
They are described as white, aged 18 to 20 and of slim build.
PC Vanessa Blackledge said: “I am particularly keen to speak to anyone who saw men running from the scene or getting into a vehicle nearby.
“I’d also like to speak to a man who came into the shop and said he saw something at the time of the incident. This man may have information that is vital to the investigation.”
Anyone with information about the incident should contact police on 101 quoting crime reference D3/12/554, or call Crimestoppers anonymously on 0800 555 111.