Another man in his 70s was injured in the incident, according to Region Kalmar his condition is unclear but "probably minor".
The police were alerted at 2 pm on Saturday to the store where the two men received stab or cut wounds. The perpetrator left the scene and after a period of searching, the police announced at 6:30 pm that a man in his 30s had been arrested at an address in Nybro municipality.
The man in his 70s is said to have been a customer and the one in his 20s is said to have worked there, says the police's press spokesperson Filip Annas to Aftonbladet earlier on Saturday.
The crime scene will be examined by the police's technicians.