Norwegian police said on Monday they had arrested a suspected shooter after receiving reports of gunfire at Oslo's largest shopping centre.
Police said in a statement that no injured people had been found and that it was safe to reopen the centre again, after it was earlier evacuated.
"As of now, it appears that there was only one perpetrator involved," the statement said.
Police spokesperson Tomm Berger told journalists the suspect, a 19 year-old, had called the police before he fired a single shot with a shotgun into the ceiling. The suspect had also been carrying a baseball bat and a knife.
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