The 30-year-old suspect, whose name wasn't reported, was due to be deported Tuesday before he was taken to Bergen's Sandviken psychiatric hospital for an undetermined amount of time, TheLocal.no reported Thursday.
"He will remain at Sandviken while doctors believe he has the need for treatment there," said his lawyer, Fredrik Verling. "I've had a brief and straightforward conversation with him. He is polite, quiet and friendly."
The man is accused of seizing a Valdres Express bus Monday and killing all three people aboard, including the driver, Arve Haug Bagn, 55. Another victim was identified as student Molland Sanden, 19. The third victim, a Swedish man in his 50s, wasn't identified, TheLocal.no said.
The alleged attacker was treated for self-inflicted knife wounds to his throat at a hospital in Bergen.