Shortly after six o'clock on Friday night, police were alerted to a furniture store on Hallsta gårdsgata in Erikslund in Västerås.
Three younger people, armed with a large knife, are said to have threatened and tried to force jewelery from the shop staff in particular.
A person must have had mild cuts.
The three must then have disappeared from the scene on dark mopeds or scooters.
The police are on site and are also looking for the suspected perpetrators.
Have they been inside more stores?
- Not as we are aware of at the moment, says Magnus Jansson Klarin
The incident is currently classified as an attempted robbery.