“The man said under questioning that he wanted to kill several people and that this was an act of terror,” the police reported.
The attack occurred when woman was paying at a cashier desk. Later, after the knife attack, the police detained a 20-year-old Russian.
He arrived in Oslo on Thursday, traveling from Russia to Sweden.
Police is investigating his ties with Islamic extremists.
The injured is at a hospital; she's in critical condition now.