A man with a firearm was suspected of opening fire in Central Oslo was arrested by Norway Police on Sunday.
No one has been injured.
Police said on Twitter that the man was detained behind Oslo's downtown cathedral, adding they have no information that shots were fired at people.
However, they were seeking witnesses.
Today's incident happened around Stortorvet, a square adjacent to the Oslo Domkirke cathedral.
Earlier on April 9, a suspect was arrested after Norwegian police neutralised an explosive device found in downtown Oslo.
Police Chief Vidar Pedersen confirmed on Saturday that the device, initially described as "bomb-like," was an explosive. The police Twitter account said it had been defused or neutralised.