A Norwegian Air Shuttle plane en route to the French city of Nice returned to Stockholm safely after receiving a bomb threat shortly after take-off on Thursday, the airline said.
"Norwegian can confirm that a bomb threat was issued against flight DY4321 from Arlanda to Nice," it said in a statement, providing no other details.
Stockholm police spokeswoman Towe Hagg told AFP that local and border police as well as tactical units were "working actively at Arlanda to gather information, follow up and take necessary measures."