Detectives are appealing for information following the attempted robbery at an off-licence in Gisburn Road, Barrowford, on Wednesday.
Around 7-15pm, a man entered Maguires in possession of a large knife or sword and threatened the lone female shopkeeper.
He demanded she open the till and hand over money, but she refused and the man fled on foot, turning into Lee Street.
He is described as white and was wearing a hooded top and scarf which covered his face.
Det. Con. Shaun Juriansz said: “Thankfully the shopkeeper wasn’t physically injured. However, she has been left shaken by what has happened.
“If anybody thinks they may have seen this man either prior to the incident or following it then I would urge them to contact police.
“I would also appeal to anyone who has any information whatsoever that they think could assist our investigation to come forward.”
Anybody with any information can contact police on 101 or Crimestoppers anonymously on 0800 555 111 or on-line at Crimestoppers-uk.org. No personal details are taken, information is not traced or recorded and you will not go to court.