“The shooting in Oslo on Saturday night means that the PST is raising the terrorist threat level from normal to extreme,” RIA Novosti quotes Berg as saying at a press conference.
He said law enforcement had known about the suspect since 2015.
According to the latest reports, as a result of shooting at a nightclub, two people were killed and 21 others were injured.
Police spokesman Christian Khatlo said that the suspect in the Oslo shooting is a native of Iran.
Norwegian police are investigating a shooting at a nightclub in Oslo as a terrorist attack.