Oslo's central station was evacuated and all train and bus service halted after a suspicious suitcase was discovered early on Wednesday.
"All the trains and the buses have been cancelled until further notice," an NSB railway official at the scene told Reuters. "Under police orders nobody is allowed to go into the station."
Norway's NTB news agency said someone had apparently placed a suitcase on an airport-bound bus near railway track 19 and then left.
A Reuters witness said the station was surrounded with police cars and fire trucks and that a large area on the south side of the station adjacent to the Thon Hotel Opera was cordoned off.
A hotel receptionist told Reuters the hotel had not received instructions from the police to evacuate.