Police learned that the intruder had entered the international terminal at 3:45 p.m. on Friday afternoon.
"We were alerted via Oslo Airport Gardermoen. A person had come in through the security control without being checked by personnel," police operation leader Åge Ødegaard told Aftenposten.no.
Airport personnel spotted the incident via security monitors, NRK (Norwegian Broadcasting) reported.
"Those working in security control saw him go through the check without showing an ID-card. After he came through security personnel lost him. He may have been an employee or a passenger, we do not have that clear yet, Ødegaard said.
All passengers at the international terminal were evacuated through gate 40 and delays were expected as everyone would have to be reprocessed through security. No planes had been evacuated and one plane that had been fully boarded when the evacuation began took off without being evacuated.
"We don't know much more than that passengers will be evacuated and that the terminal will be examined to see if there are things there that shouldn't be there," OSL information chief Jo Kobro told Aftenposten.no.
