The alarm about the incident, which took place in a store on Kristiansborgsgatan / Mästargatan in Västerås, was received by the police just before 9.30 pm.
The shot that was fired hit a wall in the store, and the two perpetrators then left the scene.
The police have launched a search operation with, among other things, helicopters, they write on their website.
The incident is classified as aggravated robbery and attempted murder or manslaughter.