Three masked men armed with bats and crowbars forced their way into the Cardigan Arms pub in The Jamb, Corby.
The offenders then threatened the occupants and stole money before leaving.
They ran in the direction of the woods at the rear of the premises where it is believed they got into a car and drove across the field.
The burglary happened sometime between 3am and 3.35am on Monday, July 13.
The three men were all wearing black clothing and balaclavas.
Anyone with any information can call Northamptonshire Police on 101 or they can call the independent charity Crimestoppers anonymously on 0800 555111.