After the shots in Oslo with two dead and at least 14 injured, the Norwegian authorities are investigating a terrorist act.
"The police are treating the case as an act of terrorism," the authorities said on Saturday.
A suspect was arrested after shots were fired around 1am in three places, including in front of a gay bar.
Everything points to a single perpetrator, said police chief Tore Barstad.
However, the police forces in Oslo have been strengthened as a precaution.
The shots were fired in the center of the Norwegian capital near the gay club "London Pub" and a jazz club, as well as a snack bar.
Police representatives discussed during the night whether the planned Pride march on Saturday afternoon can take place as planned.
"Sure what he's aiming for"
"He seemed very sure of what he was aiming at," said an eyewitness to the newspaper "Verdens Gang" about the perpetrator.
Another witness told the newspaper that the man had fired an automatic weapon and that the crime scene looked "like a theater of war".
Several people with head injuries were lying on the ground.
Heavily armed police officers in riot gear secured the crime scene.