Two people were killed and 14 wounded in the attack.
The suspect whom police have arrested following deadly shootings in Oslo overnight is a Norwegian of Iranian descent, police said on Saturday.
The man was known to domestic intelligence services and had had brushes with the law for minor infractions like knife and drug possession, police told a press conference, without naming the suspect.
Police said earlier they were investigating the shootings, which left two dead and at least 21 wounded, as a "terrorist attack".
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