Two men stole money from a bookmakers in Desborough after threatening staff.
The incident happened at about 9.30am this morning (Monday) at the Coral branch in Station Road.
The offenders were described as having scarves covering their faces.
One staff member suffered minor injuries that did not require hospital treatment.
A police spokesman said they had no information about weapons being used and was unable to confirm how much cash was stolen in the raid at this stage.
Witnesses should contact police on 101 or Crimestoppers anonymously on 0800 555111.