A man wielding a weapon threatened staff at a shop in Bourne before making off with money from the till.
The incident happened at Happy Shopper in Churchill Avenue at around 8.40am on August 18.
Police say the suspect, who was wearing a face mask, approached the store from West Street and turned right in to Churchill Avenue, entered the shop and made threats with a weapon before making off with money from the till.
He turned right out of Churchill Avenue onto West Street towards town at 08.43am.
This is the second armed robbery in Lincolnshire in the space of 24 hours this week, after an incident at a Spar shop in Chapel St Leonards on Tuesday evening.
The suspect is described as a white man wearing a blue or black hooded top, grey tracksuit bottoms and black trainers. He wore his hood up and had the cords pulled tightly round his face.
Officers and forensic teams rushed to the scene and have launched an investigation to find the person responsible.
There will be an increased police presence in the area today as officers conduct their enquiries.
Detective Constable Carl Christopher said: “This was a really distressing incident for the staff in a local shop who were just going about their business with no expectation that they would be targeted and threated in this way.
“We are conducting a thorough investigation, and would like to appeal to the public for help in identifying the suspect.
“Numerous cars drive by on West Street at that time of day, and it’s possible that they have captured the suspect on a dash cam.”
If you have any information, email [email protected] quoting incident 78 of August 18, call the non-emergency number 101 or Crimestoppers anonymously on 0800 555 111.