Two would-be robbers may have been armed when they demanded cash from a St Helens shop.
Men wearing balaclavas went into One Stop Shop on Walmsley Road, Eccleston, at 8.45pm on Sunday, July 10.
They demanded money from one of the shop assistants before fleeing empty-handed.
No-one was hurt, but staff members and customers were left shaken up.
Detectives are now appealing for witnesses as they investigate the attempted robbery.
They want to speak to anyone who was in the Walmsley Road area or the nearby shopping parade either before or at the time of the incident.
Police said the men were both wearing balaclavas and it is believed they may have been armed.
One of the men was described as white, around 5ft 10ins tall and of medium build. He spoke with a local accent and was wearing a jacket and dark-coloured trousers.
The second man was white, around 5ft tall, of slim build and also spoke with a local accent. He wore a Nike Air jacket and dark-coloured trousers.
The men are thought to have left the area in a white Volkswagen Golf with rear tinted windows.
Anyone with information about the incident is asked to call St Helens CID on 0151 777 6064 or Crimestoppers, anonymously, on 0800 555 111.