A Norwegian man was arrested after twin attacks hit Norway on Friday, Justice Minister Knut Storberget said.
The gunman has links to right-wing extremism, Norwegian TV2 reported.
"Our information is that he is a Norwegian," Storberget told a news conference. "I don't know so much about him."
Earlier reports cited police as saying that the terror acts were carried out by a home-grown terrorist.
The terrorist set off an explosion that ripped buildings in the heart of Norway's government Friday, then went to a youth camp in a police costume and gunned down youths, police said Friday.